Where can I find the deepest (or, if not strictly the deepest, notably deep) publicly-accessible floor space, in terms of raw depth under ground level or number of basements? Sea level is not immediately relevant to this question, as it relates to the ground level of the area where the building is. If the building is on the side of a mountain or hill, make a judgment call as to whether or not it is in scope.
I know that there is a publicly accessible complex underneath the National Mall in DC that includes the S. Dillon Ripley center and a few other buildings, and I believe that goes down to at least the 3rd Basement (B3), and there are several exhibits at that level.
I’m considering space other than standalone subway stations, but I will count subway stations that are IN a basement or sub-basement of a building in the sense that the station platform could be said to be IN the building itself in one of it’s basements and accessible from the rest of the building without going outside rather than buried below the foundation.
The Civil Engineering building at the University of Minnesota in Minneapolis was built below ground to save energy, and extends down seven stories and seventy feet below ground level. I’m sure there’s many deeper buildings, but that’s the deepest one I know of.
There’s a parking garage at the University of San Francisco Medical Center built into the side of a steep hill. The ground floor on one side of the building is several or eight floors below the ground floor on the other side.
Mansueto Library at the University of Chicago deserves a mention as being in this category. Other than a glass dome over the top, it is entirely underground (55ft.). However, it most of the volume is simply used by a robotic retrieval system storing 3.5 M volumes. So it isn’t foot accessible, but it is publicly accessible
This also happens at Columbia University where some buildings on the campus side are entered on the “ground floor” of 6 from the campus side but exited on the ground floor of 1 or -1 for the street access.
This may or may not fit your qualifications, but the Diefenbunker, outside Ottawa, is 100,000 square feet over four levels of reinforced concrete under a small, one-story building.
Tons and tons of university libraries that used to have closed stacks are mostly underground. The Thomas Cooper library at the University of South Carolina is IIRC 7 floors down, which is rare here as the water table is very high.
I guess this wouldn’t qualify according to the OP’s final paragraph, but I once did a tour of a gold mine in South Africa. This started in a building that housed a large elevator in which we descended 600 ft. Apparently, some mines reach depths below 10,000’ - though I doubt many of these qualify as publicly accessible.
The question clearly asks about the building with the most accessible floors below groung, NOT about depths in metres, feet or anything else.
Whilst I don’t know the answer for certain, I offer as a candidate, the Meriton Soleil Tower in Brisbane, Queensland, Australia which has 10 below-ground floors (and, for those interested, 74 above ground).
“Where can I find the deepest (or, if not strictly the deepest, notably deep) publicly-accessible floor space, in terms of raw depth under ground level or number of basements?”
which is pretty clearly asking for either number of basements or raw depth.
Vanderbilt University’s West Garage has three entrances on three different streets – two of them are to level G and one is down a roughly 10-foot hill to level S1 (for “sub-level” or “sub-basement” or “something”). Its bottom level is S8.
However: (1) it’s employee parking, although that’s unenforced on weekends; and (2) it has freestanding walls on all four sides – it’s essentially a 12-story garage built in a deep hole. (I guess that makes ventilation easier?)
No, it clearly doesn’t, as already pointed out. Actually clearly, on the other hand, the question, and all answers previous to yours, were posted over two years ago.
Not terribly deep, but large parts of Park University in Parkville Missouri are old underground limestone caverns. Even the library is underground. (At one time the school itself mined and sold limestone to support itself.)
