Cistern of the Hebdomon
Bakırköy, Turkey
The Cistern of the Hebdomon (ῦ Ἕ), known in Turkish as Fildamı Sarnıcı ("Cistern of the elephant's stable"), is a Byzantine open sky water reservoir built in the quarter of the Hebdomon (today's Bakırköy), an outskirt of Constantinople.
Archaeological site data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).