Just below the streets of Sultanahmet lies one of Istanbul’s most atmospheric historic structures: the Basilica Cistern, known in Turkish as Yerebatan Sarnıcı.
Built during the Byzantine period, this enormous underground water reservoir offers a completely different experience from the palaces, mosques and churches above ground.
Why Was the Basilica Cistern Built?
The cistern was constructed during the reign of Emperor Justinian I in the 6th century.
Its purpose was practical: storing water for the imperial center of Constantinople and nearby buildings.
The vast underground chamber is supported by 336 columns, many of which were reused from older structures.
This reuse of architectural material was common in the ancient and Byzantine worlds.
Why Is It Called the Basilica Cistern?
The name comes from an earlier basilica that once stood in the area above the reservoir.
In Turkish, the structure became known as Yerebatan Sarayı, or “Sunken Palace,” because the rows of columns rising from the water create the impression of an underground palace.
The Medusa Heads
The most famous details inside the cistern are two ancient Medusa-head blocks used beneath columns.
One is positioned sideways and the other upside down.
Their original source and the exact reason for their placement remain uncertain, which has helped make them some of the most photographed objects in the cistern.
Visiting Today
A major restoration project strengthened the historic structure and introduced a new lightweight visitor walkway.
Modern lighting and art installations also create a contemporary visitor experience while preserving the historic architecture.
Because the cistern is underground, it can provide a welcome change during particularly hot summer days or rainy weather.
Nearby Attractions
The Basilica Cistern is only a short walk from Hagia Sophia, Blue Mosque, the former Hippodrome of Constantinople and Topkapi Palace.
Its location makes it easy to include in a day exploring Istanbul’s Historic Peninsula.