It's not underground: "The majority of the facility is above ground. The only part that is underground is a subterranean corridor that links cellblocks to the

It's not underground: "The majority of the facility is above ground. The only part that is underground is a subterranean corridor that links cellblocks to the lobby." https://en.wikipedia.org/wiki/ADX_Florence https://en.wikipedia.org/wiki/ADX_Florence