# What will be the largest post-industrial man-made structure to remain standing the longest? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 20, 2015, 1:48am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443 "2015-03-20T01:48:55Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [March 20, 2015, 1:48am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/1 "2015-03-20T01:48:55Z")
The Great Pyramids are 4500 years old (at least). Petra is about 2000 years old. What is the largest post-industrial man-made structure, **that currently exists** , that will remain standing the longest? For the purposes of this question, the definition of “structure” is extremely broad, as well as how intact it must be to be considered “remaining standing”; there should be enough of it remaining that it would still be instantly recognizable for what it was to a person living today. Judging on the really old structures we still have that are mentioned above, I’m thinking something like Mount Rushmore or the Hoover Dam. Thoughts? ---
**Author:** ![yellowjacketcoder](https://avatars.discourse-cdn.com/v4/letter/y/4bbf92/32.png) [@yellowjacketcoder](https://boards.straightdope.com/u/yellowjacketcoder)\ **Post date:** [March 20, 2015, 2:54am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/2 "2015-03-20T02:54:24Z")
Damn, I was going to pick Rushmore. I know they paint the Eiffel Tower every year, but how long would it last if they stopped doing that? ---
**Author:** ![JohnT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnt/32/15048_2.png) [@JohnT](https://boards.straightdope.com/u/JohnT)\ **Post date:** [March 20, 2015, 3:09am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/3 "2015-03-20T03:09:28Z")
> [@DCnDC](#): > > The Great Pyramids are 4500 years old (at least). Petra is about 2000 years old. > > What is the largest post-industrial man-made structure, **that currently exists** , that will remain standing the longest? > > For the purposes of this question, the definition of “structure” is extremely broad, as well as how intact it must be to be considered “remaining standing”; there should be enough of it remaining that it would still be instantly recognizable for what it was to a person living today. > > Judging on the really old structures we still have that are mentioned above, I’m thinking something like Mount Rushmore or the Hoover Dam. > > Thoughts? Would you consider mines to be “structures”? I can imagine some mines lasting millions of years. Mt. Rushmore is a pretty solid guess. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [March 20, 2015, 3:33am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/4 "2015-03-20T03:33:44Z")
How about Voyager 1. It is expected to reach the Oort cloud in 300 years and pass through in in about 30,000 years. After 40,000 years it will pas within about 1.6 light years of the star Gliese 445. It is not expected to collide with anything and the “erosion” by dust in space should be minimal. I can’t recall nor find out if it’s heading out of the galaxy, I would assume it could still be recognizable after a billion years. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [March 20, 2015, 3:38am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/5 "2015-03-20T03:38:11Z")
> [@JohnT](#): > > Mt. Rushmore is a pretty solid guess. Kinda stretches the definition of “structure” a bit. Plus, I think the original plan was to carve even more of the figures but they had to curtail things when fissures were found in the rock, so it may be less stable than we think. Rather than Hoover Dam, I wonder if Grand Coulee or Three Gorges might last longer. Hoover is very tall, and with a lot of pressure behind it. If, and when, the water was to find its way through, seems like the pressure would start to break it up. Grand Coulee Dam is long and low, and without the high rock walls. If the river cut a new channel around the dam, natural erosion would take a long time to wear down that much concrete. ---
**Author:** ![Grotonian](https://avatars.discourse-cdn.com/v4/letter/g/c2a13f/32.png) [@Grotonian](https://boards.straightdope.com/u/Grotonian)\ **Post date:** [March 20, 2015, 4:09am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/6 "2015-03-20T04:09:56Z")
The Vietnam Memorial will get covered up, but once it’s dug out, wont it be still be legible after a thousand years? Or is DC too swampy? Wait, ignore that about legibility, not one of the parameters. I think it will remain as a massive granite V wall for thousands of years. ---
**Author:** ![Deeg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/deeg/32/2955_2.png) [@Deeg](https://boards.straightdope.com/u/Deeg)\ **Post date:** [March 20, 2015, 4:15am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/7 "2015-03-20T04:15:11Z")
> [@OldGuy](#): > > How about Voyager 1. Good nerdy answer! I’m not sure about a damn. Water has a tendency to wipe out things. If we ever get to @$#\* use it, how about Yucca Mountain? ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [March 20, 2015, 5:16am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/8 "2015-03-20T05:16:54Z")
Still trying to find the cite, but when Gutzon Borglum was asked about Mount Rushmore, he said he added a foot to Washington’s nose. Borglum said he did that after finding out that the Rushmore granite only weathers at a rate of one inch per 100,000 years. He wanted to give Washington another million years. I did find: > [@](#): > > I am allowing an extra three inches on all the features of the various Presidents in order to provide stone for the wear and tear of the elements, which cuts the granite down one inch every hundred thousand years. Three inches would require three-hundred thousand years to bring the work down to the point that I would like to finish it. In other words, the work will not be done for another three hundred thousand years, as it should be. [You searched for single.html – QOTD.org](http://www.qotd.org/search/single.html?qid=72370) ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [March 20, 2015, 5:25am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/9 "2015-03-20T05:25:59Z")
> [@Duckster](#): > > … he added a foot to Washington’s nose… that had to hurt ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [March 20, 2015, 5:43am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/10 "2015-03-20T05:43:21Z")
If it is ever finished the Crazy Horse Monument will be larger than Mt. Rushmore. What about canals? How long would it take for the Suez to silt up so that water no longer flowed through? I assume there are strip mines larger than Mt. Rushmore, they may not be artistic but like Rushmore the man-made part is simply removal of material that was already there. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [March 20, 2015, 6:18am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/11 "2015-03-20T06:18:50Z")
Road-beds. (Okay, they aren’t “standing” really. But they will remain detectable for an awful long time!) Here’s another bad answer: temple pillars in neo-Roman style, at least the bottom two or three drums. It’s a bad answer because only parts will remain standing, and they aren’t really post-Industrial structures, as they pretty much use the same techniques the Romans did… Have I picked at the edges of the rules enough? (It’s a common sport here!) Serious answer: a set of concrete storage buildings…somewhere. Maybe a “U-Stor” in Baltimore, or in Duluth, or in Brisbane… But a row of concrete storage blocks. There’s hundreds of thousands of 'em, and they’re just about as solid as can be, while also fairly minimal. They aren’t complicated enough to fail in any fancy way. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [March 20, 2015, 6:29am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/12 "2015-03-20T06:29:38Z")
How sturdy is the Pentagon? ---
**Author:** ![JustinC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/justinc/32/8083_2.png) [@JustinC](https://boards.straightdope.com/u/JustinC)\ **Post date:** [March 20, 2015, 8:08am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/13 "2015-03-20T08:08:17Z")
Does it have to be above ground? Nuclear bunkers were built to withstand quite a lot. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 20, 2015, 11:55am UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/14 "2015-03-20T11:55:29Z")
Landfills Also there is some radioactive waste facility that is designed to hold that stuff for 1000’s of years or something like that. ---
**Author:** ![solost](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/solost/32/11776_2.png) [@solost](https://boards.straightdope.com/u/solost)\ **Post date:** [March 20, 2015, 12:07pm UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/15 "2015-03-20T12:07:19Z")
> [@Duckster](#): > > …he added a foot to Washington’s nose… I thought Washington never told a lie! ---
**Author:** ![Zerc](https://avatars.discourse-cdn.com/v4/letter/z/82dd89/32.png) [@Zerc](https://boards.straightdope.com/u/Zerc)\ **Post date:** [March 20, 2015, 12:42pm UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/16 "2015-03-20T12:42:28Z")
In the same spirit as Voyager there is [LAGEOS-1](http://en.wikipedia.org/wiki/LAGEOS) which is predicted to re-enter the atmosphere in 8.4 million years and contains a plaque designed by Carl Sagan. ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [March 20, 2015, 1:21pm UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/17 "2015-03-20T13:21:01Z")
Are you looking for the oldest structure or the largest structure? It’s unlikely that they’ll be the same thing. If you want some of both, what’s the weighting between the two? What’s worth more, lasting for an extra thousand years or being a half million square feet larger? If you weigh very heavily towards size, and define size as the largest usable space, then the Boeing Everett Factory is the correct answer. Anything else depends on different assumptions and speculation. Probably closer to what you actually want to know too. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [March 20, 2015, 2:12pm UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/18 "2015-03-20T14:12:09Z")
> [@Trinopus](#): > > Road-beds. (Okay, they aren’t “standing” really. But they will remain detectable for an awful long time!) Considering the state of some roads I drive over daily, that were paved less than 10 years ago, a road might not out-last much of anything after a few hundred years. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [March 20, 2015, 2:25pm UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/19 "2015-03-20T14:25:06Z")
> [@Duckster](#): > > Still trying to find the cite, but when Gutzon Borglum was asked about Mount Rushmore, he said he added a foot to Washington’s nose. Borglum said he did that after finding out that the Rushmore granite only weathers at a rate of one inch per 100,000 years. He wanted to give Washington another million years. Wouldn’t cracks eventually form in weak areas, such as the corners of the mouths and eyes, thanks to freezing/thawing cycles, eventually causing the visages to crumble, a la New Hampshire’s Old Man in the Mountain? ---
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [March 20, 2015, 2:43pm UTC](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443/20 "2015-03-20T14:43:29Z")
> [@Snarky\_Kong](#): > > Are you looking for the oldest structure or the largest structure? It’s unlikely that they’ll be the same thing. I’m looking for a large man-made structure that’s going to remain in an easily recognizable state for a longer time than anything else that was built within a time period of ≈150-200 years ago to the present. The question is purposely vague. [Next page](https://boards.straightdope.com/t/what-will-be-the-largest-post-industrial-man-made-structure-to-remain-standing-the-longest/715443.md?page=2)