Wikipedia has a neat article about military citadels under London. (I seem to have forgotten how to do a link correctly, I put it at the bottom.) There is also a neat article about the defenses of Paris. The only thing we got for Washington is the Civil War defenses.
What do we know about secret bunkers, tunnels and so on under Washington? I can’t find much. A map would be nice.
https://en.wikipedia.org/wiki/Military_citadels_under_London
The only one I can think of is the Greenbriar:
Dennis
There’s the Presidential Emergency Operations Center below the White House and Mount Weather, although that’s outside of DC.
Yes, exactly. They are not part of a secret complex of tunnels. We can assume that at least some such facilities exist. Small mentions of them surface in the press. We are obviously keeping our secrets pretty well.
There are tunnels and mini-subways that connect the capital building to the senate offices. These aren’t exactly secret, but they aren’t open to the public either.
If I were building such a thing, I’d use subway construction as a cover story. So perhaps the Washington Metro was built to disguise the secret tunnels? But I learn from Wikipedia that the Metro was built in the 1970s and that seems too late for a Cold War era series of nuclear bunkers.
But keep in mind that, unlike Washington, London was actively being bombed during the Second World War, so the Brits needed underground bunkers more than the Americans.
Something like the Presidential Emergency Operations Center might be useful in a 9/11-style terrorist attack, but I doubt building some elaborate (and expensive) maze of tunnels under Washington, D.C., would be anything but a boondoggle in terms of nuclear war.
From the “NUKEMAP” nuclear explosion effects calculator, a 500 kiloton surface burst would make a crater more than 200 feet deep. (And it’s not like your bunker will be totally OK if it’s 300 feet down; even if your bunker is deep enough that you aren’t directly turned into fallout, I’m sure there would still be some horrendous shock waves that will probably cave in your roof.)
Building underground bunkers probably made sense when the threat was propeller-driven airplanes dropping conventional explosives, or maybe even when the airplanes were dropping Hiroshima or Nagasaki sized nuclear bombs. Once people started fielding weapons in the hundreds of kilotons to megatons range, I think the only real hope for survival (well, immediate survival, without getting into the issues of long-term food and water and radioactive contamination and the total collapse of modern industrialized civilization) is to not be there when the bombs go off–get on a big airplane and go somewhere very far away from Washington, D.C.
You can go through one if you set up a tour to do it first. You even get to ride the electric rail that’s been in use there for decades.
As for tunnels, there is Site R (the Raven Rock Mountain Complex), located in Pennsylvania. It’s not a secret, as there are people living nearby, but it’s pretty impressive inside (I was able to visit it when my company had a construction project going on there). I can tell you that it has huge blast doors and its own underground bus service.
Secret underground bunkers away from other strategic targets would be just fine. Even surface buildings stocked with survival gear would be fine, assuming they are a significant distance from the ground zeroes. The problem is the fallout plume will soon come and if you don’t have a way get enough feet of material between you and the fallout particles, and also filter the air and wash off contaminants from people entering and leaving, you may still die.
So bunkers that the enemy doesn’t target because they either don’t know they exist or they are too small to bother with are what would make it.
There’s an expression that applies -
“Those who say, don’t know, those who know, don’t say.”
They used to be open to the public unescorted. There was the from car strictly reserved for Members of Congress at the time. I’ve ridden it back then, in the public cars as well as the Members only car.
Some rich relatives took me to the Greenbrier, sometime around1977-1979. Didn’t get to stay there, as they didn’t like me THAT MUCH. Got to walk around the fancy grounds and building for a few hours. They showed me the entrance to the ‘secret’ bunker. Didn’t get any further than that, but as a barely preteen, I thought that was pretty damn cool. I enjoyed having that ‘forbidden knowledge’ for years, but even i realized at the time that if I knew it, it wasn’t that big a secret. I of course told my friends at school, though I at least kept it on an individual basis–no “summer vacation”-type reports in the front of the class or anything. 
Should have been a nicer day than it was. We drove for a longer time we spent there, we didn’t eat there or use any of the facilities, not even the video arcade that would have made any kid my age drool. Dunno why we even went. I can’t even imagine they cared enough to make me jealous of what they had, but it kind of felt that way.
Beautiful place, weird day for Face, and it looks like the cat was well out of the bag by the time the Carter years rolled around.
How many mirelurks did you encounter?
None—they’re closer to the river—but it’s the the reaver ghouls that I really sweated on that level. Seriously, throwing pieces of yourself at enemies, and they explodes? And you can just keep doing that forever? What was Bethesda thinking…?
I’m with Duckster: I remember walking along the tunnels next to the rail car on a school trip in 1991. They had security with bomb doggies, but otherwise let our group walk from the Capitol building to, IIRC, Dirksen. It’s been awhile. I got the impression that you could ride the tram—and we may have, I just don’t remember—but you’d have to make a reservation with your Congresscritter.
I get the feeling that NUKEMAP varies quite a bit in its crater making, and to be true, Gladstone does say that, IIRC. I don’t think the same bomb is carving out quite as big a hole in, e.g., solid granite, as it will in fill or sedimentary soils. Still probably enough to ruin your day. Even if your bunker survives the blast in one piece, as would probably be the case for something like a Minuteman LCC, you probably won’t survive the fall to the bottom of whatever hole the bomb just excavated.
Here’s a book about American efforts to save ourselves from nuclear attack.
TL : DR - While we all hope they will never have to be used, they probably won’t work anyway.
London is built on clay, so it is relatively easy to carve tunnels underneath. Here are a few of the lesser known ones.
I read the Raven Rock book. My Dad worked at Camp David and some of the LongLines programs.
Canada had the Deifenbunkers.
Looks like the government could be building some new ones as well.
Sent from my SM-G920W8 using Tapatalk
DC is also a lot of reclaimed swamp, due to proximity to the Potomac River. So, not only would building a bunker hundreds of feet down be problematic, maintenance would be costly. You’d also have to consider how to pump the water once the utilities are offline after an attack. Probably be OK for a little bit, the exit would have to be built in such a way that it’s waterproofed top to bottom so a water column that’s hundred of feet high doesn’t occur.
Doing some guesstimating, a four foot diameter by 300 foot shaft would have about a million pounds of water in it.
Be much better to get outta dodge. Which would be via VF-22 due to its higher top speed and ceiling. Doubt they’d have time to go to DCA, board a larger aircraft, and then take off.
The PEOC exists, right? There’s at least a few bunkers in DC.