Holiday apartments in London may overlook the Houses of Parliament and many vacation rentals in Barcelona take in Gaudi, but rent apartment in Istanbul and it’s architectural masterpiece is nowhere to be seen – because it is hidden underground!

The Underwater Palace or Basilica Cistern as it is more commonly known among the locals was only unearthed recently as a tourist treasure, after

Visit the amazing piece of historical architecture, the Hagia Sophia, which is the biggest mosque of its kind in Europe, and you would never know you were 500 feet away from this subterranean gem.

It was used as water storage for the Great Palace and has structures inside that ancient texts say pay homage to the slaves that died among the 7,000 that worked on its construction.

The water was used for the Palace gardens and the cistern itself was a major trading ground back in the day.

The artwork inside the beautiful underwater tunnels that have been painstakingly lit and restored includes the head of Gorgon, Medusa, who legend has it famously turned warriors to stone with her gaze.

The Underwater Palace is considered so spectacular it was used as the backdrop for many films, including James Bond’s Russia With Love in 1963 and in the finale of the 2009 movie, the International.

In total the underground chamber measures 140 meters by 65 meters and holds a staggering 100,000 cubic meters of water at height, but it lies virtually empty today, making it easier for tourists to get around and marvel at its architectural intricacy.

Visit Istanbul’s Hagia Sophia, but don’t miss what may be the best example of Byzantine architecture yet, hidden underground.