Beneath a busy roundabout in Sultan Ahmet, you can find a vast underwater cistern complete with fish and the inexplicable upsidedown head of the Medusa..

Across the road from Aya Sofya is the entrance to this magnificent underground reservoir built by the Byzantine Emperor Justinian who reigned from 527 – 565. 

It’s called the Basilica Cistern in English because at one time there was a church on top of it. 

One of its Turkish names ‘Yerbatan Sarayı’, which literally translates as ‘Underground Palace’, we think fits the place much better, as it truly is a magnificent construction.

It is a huge rectangle, 140m by 70m, supported by 336 columns many of which were cannibalized from existing Roman structures in what was then Constantinople. 

Two of the columns famously have carvings of Medusa in their bases – it is not known where they came from, or why one of them has been placed upsidedown.

The cistern continued to supply water needs for this quarter of the city throughout the Ottoman Empire before falling into dereliction sometime in the nineteenth century. 

Locals continued to use the water from wells in their gardens, and it was this that led to its ‘rediscovery’ and the removal of 50,000 tonnes of mud in 1985 – 87 during its most recent restoration.

It featured in the film ‘From Russia With Love’ and nowadays is high on the tourist ‘must-see’ list in Istanbul. 

Chamber music concerts are performed on a platform over the water in the cistern – a wonderful experience if there is one scheduled while you are in Istanbul.

There is a good range of information in English, and the shallow water in which the columns still stand si teeming with some pretty impressive looking fish.

There are other cisterns you can visit and, it is alleged, some still to be discovered, but the Basilica Cistern is certainly the one to see.