For some of the other English-speakers who've stumbled across these photos from other sites and haven't browsed some of the other comments, it's a decommissioned Russian nuclear sub base in Balaklava, a town in Crimea, Ukraine. Apparently it was designed to be virtually indestructible, even against a direct nuclear impact. When the Soviet Union collapsed in '91 the torpedoes and low-yield nuclear warheads were removed, and in '96 when the last sub was moved from the base it was converted into a museum.

And to russos, these are some pretty amazing photos. Looking at them while listening to the soundtrack to Riven was very unsettling—definitely a neat experience. Thanks for posting them for all to see!