The Basilica Cistern of Byzantium: an Ancient Wonder

"The Mystery of the Sinking Palace"

Photos and a pretty good description of a cistern called the "Sinking Palace" by people in Istanbul/Constantinople/Byzantium. I seem to remember that the place was built around the time when people were starting to call Byzantium Constantinople. The city's current name is Istanbul.

The Curious Expeditions blogger identifies "Yerbatan Sarnici" as the site's official website. (There's an English version available, as well as several other languages: look for the Union Jack.)

The Wikipedia has a decent article about the cistern, too.

(A comment on the Curious Expeditions post calls the "Sinking Palace" a hoax, perpetrated by Istanbul tourism promoters. I understand the feeling. The place looks too good to be real. But I've run into reliable references to it for decades. Calling it a hoax is a bit like calling New York's Times Square a hoax, intended to lure New Year's party-goers. ;) )