Andrys, I believe this is a turbe, or tomb. From Lonely Planet: "The tomb was built in the style of a Seljuk kumbet (tomb topped by a dome) for Colak Abdi Pasa, Ishak Pasa and their families. It's richly decorated with a mix of Selcuk carvings; note the faceted stalactite work, and Persian relief style evident in the floral decorations,; steps lead down to the site of the sarcophagi."
Thank you for your comments on my Istanbul gallery -- it's nice to know someone appreciates it! I actually have a huge number of pictures of Turkey taken over the six years I've lived here, but the older ones (on my Webshots site) were taken in film and scanned (not such great quality :-). I'm now trying to build up my digital collection with my various galleries here on PBase. I've also written quite a few articles on many of the places you visited, so I'm enjoying going thru your albums. Some very nice shots -- more comments later. Helen