Negative Building

[M.K.]

What is the deepest bldg in the ground???

I know that bldgs are normally positive ones against the sky, but we do not have much information about the negative ones, I mean the bldgs which goes inside the earth in other direction against the ground. We know some deep complicated mines, which I would consider as factory, but i have less information of much storeys for human beeing inside the ground. I have heard once but have no more idea where is or how looks like.

[MayDay]

Due to soil conditions, several of the skyscrapers in downtown Cleveland are built on caissons that go 250-290 feet (85m to 88m) into the earth to reach bedrock.

There's also a salt mine that goes under Lake Erie - it's accessed by a shaft that's 1,750 feet deep (533m). The tunnels extend 4.8km (3 miles) out under the Lake.

http://www.wcpn.org/news/2001/01-03/0301salt-mine.html

[Alpha]

TauTona Gold Mine in Carletonville, South Africa is 3.6 kilometres deep ( http://en.wikipedia.org/wiki/TauTona ). There are other gold mines in South Africa with comparable depth.
There are no deeper "floors" in the world, but some drillings went down until 14 kilometres.

[Alpha]

TauTona Gold Mine in Carletonville, South Africa is 3.6 kilometres deep ( http://en.wikipedia.org/wiki/TauTona ). There are other gold mines in South Africa with comparable depth.
There are no deeper "floors" in the world, but some drillings went down until 12.62 kilometres ( http://en.wikipedia.org/wiki/Kola_Superdeep_Borehole )

[M.K.]

Thanks guys. I know about Salt and Gold/Diamond mines, but I heard once an experimental bldg inside earth was built like the Bunkers for people living and was proposed to be sold.

[Zerton]

I know NORAD is deep.

I've always heard the Pentagon goes pretty deep.