It was built to store and supply water to the Great Palace of Constantinople and other buildings in the city.

The cistern measures approximately 138 meters long and 65 meters wide, capable of holding about 80,000 cubic meters of water.

It is named after a nearby basilica that once stood above the cistern before it was converted into a water reservoir.

Yes, it is open to the public as a museum and major tourist attraction.

It is easily reachable by walking from Sultanahmet Square or by tram to the Sultanahmet stop.