Cistern of Philoxenos, Roman cistern in Istanbul
The Cistern of Philoxenos, an ancient water reservoir marvel, lies beneath the streets of Istanbul.
Built by the Romans in the 4th century, the cistern provided water storage for the Great Palace of Constantinople.
The Byzantine heritage of the Cistern reflects Istanbul's layered history.
Today, it is a tourist attraction open to the public after extensive restorations.
Known as the Binbirdirek Sarnıcı in Turkish, this underground structure is one of the largest of its kind.
Architectural style: Byzantine architecture
Source: Wikimedia