Approach to Rivendell

[Valandil]

Why does Gandalf seem to have such a hard time finding the way to Rivendell in The Hobbit? Although Boromir later says something in reference to the place being hard to find (in 'Council of Elrond'), Gandalf should have apparently been there many times before.

Also - as they are approaching it, the descriptions just seem so odd to me - of the deep narrow valleys suddenly opening up before their feet. It makes you wonder how they made any progress at all.

And also - the location where they met the trolls seems so much further from Rivendell in The Hobbit than the same place seems to be from Rivendell in LOTR.

Just puzzling - that's all. Maybe they had swung around and were coming from a different direction, maybe Elrond didn't appreciate everybody knowing how to get there, so Gandalf was obliged to use a long way around. But as I re-read closely, it almost seems I'm reading about two different places in the two different accounts.

Hmmm... did Rivendell move?

[AndMorgothCame.]

The Hobbit has always come off as a more commercial (certainly different) writing than any other Tolkien book. Though it is my favorite, it is certainly unlike any other novel he has ever written. I agree with you completely, and I think that he left more open in this book than any other novel. In my opinion, it was more or less that Gandalf hadn't been there for a while, and got temporarily lost in the "majestique" that surrounded Elrond's fortress. Overall, as precise as Tolkien has always been, I think he wrote these descriptions before he wrote the exact geography of the area. Thoughts?

[Wilhelm]

In LOTR it took 2 days to get from the Trollshaws to Rivendell. On October 18th they found the stone trolls and on October 20th Frodo arrives in Rivendell. Much of that journey is by horse, Frodo is wounded and they are in a hurry.

In the Hobbit it's not so clear but, it looks like it took the Dwarves 3 or 4 days to get to Rivendell by foot (vaguely described in the first paragraph of "A Short Rest").

These two time frames seem plausible and comparable for the circumstances.

In LOTR, JRR does not talk about any issues that may occur between the Bruinen and the House of Elrond - Frodo passes out after on the river's shores and wakes up in Rivendell. It is actually this part of the journey where Gandalf and co. have trouble in the hobbit. In "A Short Rest" they cross the river in the morning and arrive at Elrond's house after dusk. Although they do complete this part of the journey in a day, JRR does spend a fair amount of time describing what they are going through and we learn that they are slightly off track (the elves help them get back on the right track around dusk).

It sounds like it's the part of the Journey from the shores of the Bruinen to Elrond's door where it's complicated and people get lost. We never hear about this stretch in LOTR (as Frodo passed out) and I guess we can assume that Glorfindel's horse knows the way better than Gandalf did.

[Lefty Scaevola]

Or you can assume that Male Dwarves are too stubborn to ask for directions.

[Alcuin]

Rivendell was near the Great Eastern Road, the ancient Dwarven route between the Blue Mountains and the Iron Hills. The High Pass was, after the Dimrill Stair, the principal pass over the Misty Mountains. The Dwarves used the road all the time, as did other travelers. If Rivendell had been a town of Men, it would have been a major stopping-place and trading post; it was not. Travelers didn’t know how to find it: it was hidden. How could that be?

I think Elrond and the other Eldar of Rivendell concealed the way to Rivendell. It was probably a difficult place to find anyway; but one way to explain Gandalf’s difficulty in finding the correct path was that Elrond had recently changed whatever methods he was using to hide the way in. In the context of The Lord of the Rings – which had not been written or even conceived when The Hobbit was put on paper – he had every reason to do so, because Estel was ten years old and hidden there. If Gandalf had not been there since the required last change in approach, even he might have difficulty navigating Elrond’s methods.

As for Glorfindel’s horse finding its way back to Rivendell, it is possible that it knew the way, but after the flood at the Ford of Bruinen, it stood beside Frodo, who had fallen off, until Glorfindel, Aragorn, and the other hobbits reached him. We must suppose that Frodo was loaded on the back of Asfaloth and then the company hiked back to Rivendell.

[Earniel]

Originally Posted by Alcuin

I think Elrond and the other Eldar of Rivendell concealed the way to Rivendell. It was probably a difficult place to find anyway; but one way to explain Gandalf’s difficulty in finding the correct path was that Elrond had recently changed whatever methods he was using to hide the way in.

If you put it that way, it is not unlikely that Elrond used some sort of spell to hide the entrance to Rivendell. Even though it is never actually mentioned in the text that the entrance is magically hidden. Unless the Elves didn't think it was that magical, they had not quite the same definition of magic as humans would.

It is possible Elrond used the spell or a similar spell that appeared to be woven in the grey Lorien cloaks. They too hinder detection.

[Valandil]

Very interesting idea Alcuin!

Nice to see that - even when there's something that didn't totally seem to fit (in my mind, at first), somebody around here can come up with a reasonable explanation for it.

[Alcuin]

Originally Posted by Eärniel

If you put it that way, it is not unlikely that Elrond used some sort of spell to hide the entrance to Rivendell. … Unless the Elves didn't think it was that magical, they had not quite the same definition of magic as humans would.

It is possible Elrond used the spell or a similar spell that appeared to be woven in the grey Lorien cloaks. They too hinder detection.

I did not say that it was “magic,� but I agree that is what we might call it. In her conversation with Frodo and Sam, Galadriel told Sam,

…this is what your folk would call magic…; though I do not understand clearly what they mean; and they seem also to use the same word of the deceits of the Enemy.

I don’t believe it was “magic� (morgul) to the Elves: it was simply how the Elves interacted with the world around them: how they made things, how they altered their environment. If this is what Elrond did, then I agree, it is certainly to denizens of Rivendell like the Elven-cloaks of Lórien: not “magical� to the Elves, but seeming so to the mortals in the Company of the Ring.

On this subject, there is a sense of loss when we read that when Sam admires the Elven rope made of hithlain as he prepares to leave Lórien, the Elves tell him that had they known that he had a deep interest in rope, they could have taught him much, but now his time to learn was lost, and he had to be content with their gift. Much that the Elves knew was lost to Men: and the same may have been true of whatever means Elrond and his householders used to preserve their privacy in the approaches to Rivendell.

There is another issue here: how did Aragorn view such works? Certainly not as most Men would: he grew up in Rivendell as Elrond’s foster-son. He may well have understood them and even seen them for what they were: works of the Eldar; he might even have been able to construct them to some extent himself. An example of this could be his treatment of Frodo’s morgul-wound in the wild, and his comment about treating Black Breath in Minas Tirith: “Would that Elrond were here, for he is the eldest of all our race, and has the greater power.� Afterwards he sent for Elladan and Elrohir, and together the three of them treated those under the spell of the Nazgûl and those suffering the wounds and hurts of war: he used they same techniques as they. In this respect, Aragorn returned to the ancient grace of the first Númenóreans, who had lived intermingled with the Elves at the Mouths of Sirion after the ruin of Doriath.

Originally Posted by Valandil

Nice to see that - even when there's something that didn't totally seem to fit (in my mind, at first), somebody around here can come up with a reasonable explanation for it.

It requires a bit of imagination, and it cannot be “proven� with published texts. It does appear to fit the available storyline and tie into The Lord of the Rings an aggravating dangling thread from The Hobbit.

Of course, we are left with two final problems: did Glóin find Rivendell more easily because he had been there before? And if this assertion of unusual difficulty in finding the road to Rivendell is correct, then how did Boromir find it at all?

[Valandil]

Gloin and Boromir... interesting, but for them it's possible to suppose that they were guided by an unseen hand. Sort of led to their divine appointment.

Another interesting case is Bilbo - when he left Bag End with a Dwarf companion, and eventually landed at Rivendell. But, being such an Elf-friend as he was, he may have been brought there.

[Wilhelm]

To clarify - my statement that Asfolath was able to find the way to Elrond's house better than Gandalf was a "tongue in cheek" comment. Although the horse may know the way I don't think it matters as Glorfindel and Aragorn were right behind and both have intimate knowledge of finding their way to Rivendell (and as Alcuin pointed out, someone had to pick Frodo up). Subtle humour doesn't always work in writing and I need to refrain. My bad.

I really like the concept that Elrond is hiding Rivendell to protect Aragorn. I never gave much thought as to the motivation behind making Rivendell difficult to find I simply accepted that it was hidden. The chronology works very well.

A factor that would make hiding Rivendell challenging (and perhaps another reason to hide it) is that it is very near the end of The Great East Road. It does seem strange that a road ends at a place that is hidden. I don't know much of the history of the road and accept that it may simply be a relic from a previous age but, in the latter part of the 3rd age it ends at the Ford of Bruinen on the borders of Rivendell. I suspect this would make hiding Rivendell a challenge (one that Elrond could obviously overcome).

[Alcuin]

Originally Posted by Wilhelm

To clarify - my statement that Asfolath was able to find the way to Elrond's house better than Gandalf was a "tongue in cheek" comment.

Of course! And well-humored, too.

Originally Posted by Wilhelm

I really like the concept that Elrond is hiding Rivendell to protect Aragorn.

Remember that it is backward-fitting to the story, though: Tolkien had not conceived of Aragorn when The Hobbit was written: Aragorn appeared much later: the character who immediately preceded him in that position in the story was a hobbit with wooden shoes named “Trotter.” Many elements of Trotter remain in early appearances of Aragorn.

Originally Posted by Wilhelm

A factor that would make hiding Rivendell challenging (and perhaps another reason to hide it) is that it is very near the end of The Great East Road.

The Great East Road ended in the Iron Hills beyond the Lonely Mountain. The Ford of Bruinen was probably part of the main road, though that is an assumption. (Maybe it was not?) The clear implication is that to get to Rivendell, a traveler had to leave the main road. Rivendell was near the road, but unless you knew the way, you were unlikely to find it on your own. Aragorn told Frodo and Merry on Weathertop that “Some say [Rivendell] is so far, and some say otherwise. It is a strange road, and folk are glad to reach their journey's end, whether the time is long or short.” That sounds to me as if some people wandered longer than others to arrive at their destination; why, moreover, would it be a “strange road”? After all, the Great East Road simply climbed into the High Pass and went over the Misty Mountains: there’s nothing strange about that, although it might have been an arduous trek over the mountains, like going over St Bernard’s Pass in olden time. The valley of Imladris is described as “hidden,” which might not be so difficult in such mountainous terrain, particularly if Elrond were using “regular Elvish tricks,” as Gorbag might put it. Aragorn understood Elrond’s methods, however: he continued his conversation with Frodo and Merry by telling them, “I know how long it would take me…: twelve days from here to the Ford of Bruinen,” which is apparently quite near Elrond’s doorstep if you know the way.

[Wilhelm]

It is for certain a traveler had to leave the main road to find Rivendell. In my estimation, that is where time spent searching seems to be dependent on the traveler.

I don't want to side track this post with a discussion about the Great East Road but I'm trying to figure something out. I am left with the impression that the main road ended at the Ford of Bruinen and after that other roads would lead one to mountain paths or tunnels (High Pass, Redhorn Pass, Moria) which could be used to take a traveler over/through the Misty Mountains. And the traveler would pick up a different road on the other side. I am now thinking I have misunderstood that.

I am guessing here but, are the High Pass and the Old Forest Road simply parts of the Great East Road that go by another name? That seems to be the likely route to the Iron Mountains. On another point, I always thought one had to be in Imladris before one could find the start of the High Pass (this too may be incorrect).

Thx!

[Alcuin]

I looked for a citation that the Great Road (which the Shire Hobbits referred to as “the Great East Road” because its main course ran eastwards from the Shire) ran all the way to the Iron Hills. I found none. However, I offer the following:

The Men-i-Naugrim, literally “Road of [the] Dwarves”, was of great antiquity. It originated in Doriath, where the Dwarves of the Blue Mountains traded with King Elu Thingol from their cities, Nogrod and Belegost. From those cities it ran to Cirith Forn en Andrath, the “Northern Pass of [the] Long Climb” or High Pass just east of Rivendell. On the other side of the Misty Mountains, it ran down to the Old Ford, many miles south of the Carrock where Gandalf and Thorin & Co were carried by the eagles, where the ruins of an ancient stone bridge were used to ford the Anduin. The author of the Encyclopedia of Arda notes that “the old bridge over the Anduin at the Road's western end lay almost exactly halfway between the ancient Dwarvish meeting-place at Gundabad to the north, and Durin's mansions of Khazad-dûm to the south.”

The road then ran as the Old Forest Road through Mirkwood. This was the route that Beorn warned Thorin & Co against using because Goblins had begun to frequent the route. Tolkien’s maps show this emerging from eastern Mirkwood one hundred miles or more south of Laketown: presumably the Dwarves either marched north along the River Running or travelled on the river to Erebor. From the Lonely Mountain, the road ran at least to the Iron Hills, and possibly beyond that to other ancient Dwarf-mansions.

Where the road ran through Arnor, the Númenóreans maintained bridges over the Brandywine and Hoarwell. When Hobbits settled the Shire, one of the few duties assigned them by King Argeleb II was the upkeep of the Brandywine Bridge. The bridge over the Hoarwell (Mitheithel) was called the “Last Bridge”.

I don’t believe this was all one vast road-building enterprise, but rather an improvement on the routes first by the Dwarves, and later in part by the Númenóreans. The bridge over the Anduin was the last place that river was bridged according to footnote 14 of “Disaster of Gladden Fields” in Unfinished Tales. (Tolkien’s footnote cannot be entirely accurate: there was a famous bridge over Anduin at Osgiliath far to the south that was a considered a wonder of Númenórean engineering. It was also possible to ford Anduin at the Undeeps south of Lórien, so it should also have been possible to bridge the river there, too.) That essay says early on that Isildur planned to use the bridge and the High Pass to get to Imladris. I presume that the Dwarves built the original bridge over the Anduin, but it could have been first constructed by the Númenóreans; however, the Baranduin and Hoarwell could not be forded where the road crossed them, so the original bridges were almost certainly built by Dwarves, and I think this one was, too.

The Seven Houses of the Dwarves maintained contact with one another: they were all represented late in the Third Age at the Battle of Nanduhirion, for instance, where Thorin II received his sobriquet “Oakenshield” and Dain II killed Azog before the Gates of Moria. Their system of roads was probably not like Roman roads – well-planned, well-constructed, and well-maintained – but I think the bridges were important constructions first added by the Dwarves for their purposes that other folk used.

I grew up not far from the Natchez Trace, a New World road of great antiquity. A modern highway runs the route now, but I have hiked along part of the original trace, and even today it is quite clearly a road. As far as I know, there were no bridges over any of the rivers along the Natchez Trace, but other traces (the word used in that part of the United States for American Indian roads) connect to it. I imagine that the Dwarf roads were much the same: dirt tracks for the most part, but reasonably straight, maintained near important settlements where there were functioning formal governments, and interconnected.

While several roads are mentioned in Tolkien’s work, the other main road about which Tolkien gives us a good deal of information is the North-South Road, which ran from Fornost Erain to Osgiliath. That road was deliberately built by the Dúnedain and included a famous bridge of their construction at Tharbad over the Greyflood (Gwathló), although it is possible that they merely improved an already-existing trade route here, too. At the time of the The Lord of the Rings, folks in the Shire and Bree called it The Greenway, but the Bridge of Tharbad had been ruined only a little more than a century, during the lifetime of Aragorn’s mother.

[Wilhelm]

Thank You Alcuin.

It does seem likely that the Great East Road, High Pass and Old Forest Road are the remnants of the trade route used by Dwarves in ancient times (IMO), I think I was stuck on the name "Great East Road" and felt it had to be a constant. The re-making of the world, Kingdoms rising and falling, borders changing and the creation of places like Rivendell complicate the situation. New inhabitants will change the names of things that are ancient as they become part of their society. Things like that are evident in our history (Istanbul/Constantinople, New York/New Amsterdam, Myanmar/Burma, etc...)

In building (and/or in hiding) Rivendell I'm theorizing that Elrond contributed to the complexities. The remnants of the piece of the ancient dwarven road from the Ford of the Bruinen to the high pass may have been altered/eliminated. By the end of the 3rd age, it appears as though that part of the route had been eliminated or altered enough as to be difficult to find. Like I said, it's a theory.

[Alcuin]

I don’t think the old road or the approaches to the High Pass were removed, eliminated, or even altered. Elrond’s best bet was to conceal the side-road(s) that lead to Rivendell, and in rocky, semi-mountainous terrain, that might not be too tough. In The Hobbit, Bilbo (Tolkien) wrote in the chapter “A Short Rest” that there were

[very deep] gullies … with waterfalls in them … dark ravines that one could neither jump nor climb into … [and] bogs… The … path was marked with white stones, some of which were small, and others were half covered with moss or heather.

Bilbo describes the journey from the Ford of Bruinen to Rivendell as lasting from morning until evening just before midsummer’s day, the longest day of the year. Gandalf had trouble finding the way for some reason, even though he “seemed to know his way about pretty well.” Glorfindel and Aragorn, who were both thoroughly familiar with the way to Rivendell, reached the valley several hours after Frodo collapsed on the riverbank above the Ford where the Nazgûl were swept away.

Bilbo’s telling in The Hobbit makes it sound as if The Last Homely House is a settlement along the main road, but that isn’t possible: everyone would stop at Rivendell if they were given the opportunity, and as I wrote earlier, that is exactly what would be expected for a settlement of Men: traffic, commerce, and trade would be the desirable norm. Elrond and his folk, however, kept to themselves, avoiding contact with Men and Dwarves. Dwarves used the road quite regularly during Bilbo’s and Frodo’s time, passing through the Shire. Frodo gathered news from them, and the Dwarves were familiar with Hobbits, whom they regarded as poor simpletons. There was enough traffic along the road to keep The Prancing Pony in business until the War of the Ring nearly shut Barliman Butterbur’s business down when traffic fell off to nearly nothing. Thorin Oakenshield overtook Gandalf on the road, apparently just east of Bree: Thorin may well have been returning to the Blue Mountains from visiting his cousin Dain in the Iron Hills: as far as I know, there were no longer any other Dwarven settlements along the road between the Blue Mountains and the Iron Hills; though perhaps Thorin had been on a business trip to trade or negotiate some arrangements with some settlement of Men. (My bet would be the Iron Hills, though: his head was full of plans to overthrow the Dragon and return to Erebor, which he must have passed on a return journey from Dain.)

One reason Aragorn and Frodo and the other Hobbits did not meet anyone else along the road after Bree may be that the Nazgûl scared everyone else away! They were, after all, in the habit of asking people for news of “Baggins”, and they knew that the Ringbearer had slipped their net in the company of a Ranger. I doubt they had any compunctions about killing or maiming lonely travelers who displeased them or unsuccessfully tried to flee from them, and they were terrifying by design!

The question of how Rivendell was “hidden” right off the main road through its territory bothered me for many years. Boromir said, “many had heard [of the house of Elrond], but few knew where it lay.” From the maps, it appears to me that Rivendell was north of the main road, and from the descriptions of its approaches provided by Tolkien, you could not simply march up the banks of the Bruinen to get there: perhaps the little river passed through a deep, narrow defile, and it would be impossible to ford, swim, or row up a swift-running mountain stream in that case. Bogs at the top of the defile would prevent curious travelers or spies from simply following the river from a higher elevation. Other deep gullies and ravines meant that you could not simply set off northward from the road even if you knew the right direction. To me this suggests that someone headed to Rivendell who knew the way would get off the road, turn east and climb the foothills to avoid other ravines, and then double-back to travel west several miles before finally descending into the valley of Imladris. The Elves seem to have changed the correct path from time to time, possibly by using the bogs. The journey from the Ford to Rivendell could be completed from morning to evening if you knew the way. That probably means that it was less than 20 miles, and given the rough terrain, might not have been even 10 miles. Of course, Elrond probably had sentries along the way, so anyone who wasn’t welcome was either diverted or otherwise “discouraged” from proceeding; while welcome visitors who became lost (Boromir?) could be intercepted and assisted; meanwhile, people approaching the valley were identified and reported long before they reached their destination.

None of this is “canonical,” but I think it fits the evidence we’re given.

[Wilhelm]

It is a tough one to reconcile. We perceive what happens after the Ford of Bruinen differently - and that's ok. I feel that the Road becomes so hidden or confused that it can no longer be considered the main road - I feel it is a hidden path to Rivendell which continues to the High Pass. You believe that the main road continues and Rivendell is off on a separate hidden path. We all agree that it is confusing and tricky to pin down.

There is a book called Journey's of Frodo (by Barbara Strachey) that attempts to create an atlas of Frodo's journeys. She makes assumptions throughout but, looking at her work and trying to piece it back to the books is always interesting. In the section about Rivendell she indicates that she based her map on 3 drawings made by Tolkien. I would love to get my hands on copies of his drawings - it might help. In her book the East Road seems to stop at the Ford. I consider her work interesting, not definitive, so with that and a couple of dollars we could get a cup of coffee at Starbucks.

You mention the one aspect of it that drives me crazy as well. Seeing as there is a stream that runs past the last homely house - a stream that ends at the Bruinen, you would think that someone would find Rivendell by following the stream from the main river back to Rivendell. It's just too simple. You are right - there must be some navigational issues preventing this. In the foothills it seems plausible that a waterway could divert underground or travel through an impassible valley.

A great discussion - I wish we could find a smoking gun.

[Alcuin]

The smoking gun here may be that the High Pass was still in use. There is little doubt that, in “The Quest for Erebor� in Unfinished Tales, Gandalf was headed to the Shire from Rivendell, from east to west along the Great Road, when he was overtaken by Thorin Oakenshield. That means that both of them were moving west. Now, Thorin would not be using that road to Ered Luin if he did not cross by the High Pass: had he come over the Dimrill Stairs, it would’ve been shorter to go up the Greenway. But the Greenway was far less used than the Great Road. So unless the Dwarves, who we know from Tolkien’s frequent references to their traffic on it, used the old Men-i-Naugrim regularly and frequently, had some other way over the Misty Mountains, the road had to be in plain sight. Rivendell was hidden, but the road to and from the High Pass, in order to be useful, could not be.

[Wilhelm]

The high pass was absolutely in use. I agree.

The only way my position is tenable would be if all people using the pass went through Imladris. That is simply crazy talk if Rivendell is truly hidden. There had to be more traffic over the pass than went through Rivendell. There had to be another route that did not touch Rivendell.

The smoking gun indeed.

Awesome - Thank you!

[Alcuin]

Thank you for pushing so courteously!

We still have a final loose end or two: why was Rivendell where it was, and why did Elrond hide it as he did?

Sauron launched a seven-year war against the Elves of Eregion in Second Age 1693 to seize the Rings of Power and take control of Eriador. In II 1695, Gil-galad, last High King of the Noldor, sent Elrond with a small force from Lindon to Eregion to buttress its defenses. We must consider the situation: Eregion was begun by Galadriel and Celebrimbor as a land they could themselves rule, basically without regard to Gil-galad. (Until the last year or two of his life, Tolkien was using the premise the Galadriel was ambitious and wanted to rule in her own right: hence the severe temptation she suffered when Frodo offered her the One Ring.) After Galadriel rightly warned the Noldorin smiths of Eregion against Annatar, Sauron in disguise, she found herself unwelcome in Eregion and departed. But when Celebrimbor and the smiths discovered Sauron’s scheme about three hundred years too late, they repented and turned to Gil-galad for help, willingly submitting themselves again to his rule. Elrond was not only an ally coming to their assistance with a military force, I think he was also, in effect, a viceroy or governor for Gil-galad.

When Eregion was overrun in II 1697 and Celebrimbor was killed, Elrond, the Elves he brought from Lindon, and the Noldor of Eregion found themselves cut off from Gil-galad. Some of them were able to flee through Moria to Lórien; the rest he led north and founded Rivendell. Why did he choose that site?

It isn’t difficult to determine. From Imladris, there were two means of escape: the High Pass into the Vales of Anduin, or north into what later became northern Arnor, through which they might once again reach Lindon in the worst extremity. (Mount Gundabad was still under the control of the Dwarves in those days, so they might also have sought refuge there.) That was good defense.

Imladris also constituted a threat, albeit a small one, to Sauron’s rear: it left Elrond’s force in Eriador and “in the game�. It also meant that the Elves controlled the High Pass: they could move allies and supplies in from the Vales of Anduin, deny any sending-force Sauron might have along the upper reaches of Anduin access to Eriador by that route, and give Elrond access to harry any such force by crossing over the mountains himself. Even from a weak position, that was good offense.

Sauron did not possess a palantÃ*r, and there do not seem to have been any spy satellites or spotter planes, so if Elrond screened his position well, his refuge would be difficult to find. Elves seem to have become increasingly obsessive about their privacy as their sojourn in Middle-earth wore on: the Elves of Rivendell had nearly 47 centuries to devise new ways to hide themselves from unwanted visitors before Thorin & Co arrived.

[Wilhelm]

I agree with what you're saying. I'll add my 2 cents as well.

Choice of Location: The specific location could be based on any of the things you have stated. I would add to it that it could also be based on defensive reasons. The narrow, twisting paths through that area would force an attacking army into a narrow column and would make for a highly defensible position (not unlike the Khyber Pass or Thermopylae). This could have been top of mind in the 2nd age.

Hiding Rivendell: I believe Rivendell was primarily hidden out of a preference for privacy. Rivendell was hidden from friend and foe - even invited guests like Boromir. I don't believe the primary reason for hiding it was for defensive reasons. Yes - It is difficult to attack something you can't find but, ultimately I suspect a determined foe would find Imladris (after all it is within a days walk of the main road). Rivendell in the late 3rd age never struck me as being on a war footing - it was always somebody's home. Contrast the quiet arrival of guests to Imladris with the greeting the fellowship received upon entering Lothlorien. If you were hiding something for defensive reasons I would think there would be more of an ongoing military presence.

The location of Rivendell (chosen in the 2nd age) was probably based on military factors but, by the time we get to the end of the 3rd age, hiding it seems more likely to be a preference for privacy (or to keep a secret).