Visit the Sunken Palace, the city's largest and most impressive Byzantine underground reservoir, for a tourist experience unique to Istanbul.
Although Istanbul is famous for its many towering architectural landmarks, fewer people are aware of the incredible feats of engineering to be found beneath its foundations. The stunning Basilica Cistern is one of hundreds of cisterns that were used to store water to meet the needs of Byzantine Constantinople. Known in Turkish as Yerebatan Sarayi, or Sunken Palace, this enormous subterranean structure was commissioned in the 6th century by Emperor Justinian, and is one of Istanbul's literally hidden gems.Built to supply the Great Palace, the Basilica Cistern is now the best-known of all Istanbul's cisterns. For centuries of its history, however, it was forgotten and became a dumping ground for all kinds of debris, including corpses! It wasn't until the 16th century that it was rediscovered, at which point it reprised its former function as a cistern, this time supplying water to Topkapi Palace. Nowadays it's the perfect place to get away from the heat and bustle of the city above. Music and soft lighting create a romantic atmosphere and raised walkways keep you high and dry while you survey the shadowy deeps.You might need to stop off at the café for a Turkish tea after your visit, as the vast cistern, with its 336 marble columns, covers nearly a hectare. This isn't so surprising when you realise that it used to hold over 80 million litres of water, pumped via 19 kilometres of aqueducts. When you get to the north-west side, keep an eye out for the upturned Medusa heads at the base of some of the columns to the rear.The Basilica Cistern is open every day and visits last around an hour. Tourists have to pay, but it's worth it for a chance to experience something a little bit different and escape from the summer sun. To get here just hop on the tram to Sultanahmet Square in the Old City.