>> reporter: from secret passage ways aboveground to an entire world below. you see, seafood importer want aid really beg house. and when zoning laws wouldn't let him build up, well john? went down. way down. five stories belowground. >> we're approaching 20 feet below the ground. >> i feel like we're in another world. >> at the end of the labyrinth, two stories below ground, well everyone needs a hamam, right? >> a hamam is a wet spa. >> reporter: i don't know what to say right now. i am kind of speechless. >> this is all 24 carat gold. >> you can do a mud bath in the subterranean level of your spa. >> everybody needs a mud bath. >> what is an underground mansion without a tennis court made to u.s. open specifications of course, 50 feet below ground big enough to double as a ballroom. >> it can withstand a pretty