Basilica Cistern

  Built in the 6th century, Basilica Cistern sits beneath the bustling streets of Istanbul, just a short walk from Hagia Sophia. This underground water reservoir, originally constructed to supply water to the Great Palace of Constantinople, spans an impressive 138 meters in length and 65 meters in width. One of its most intriguing features is the 336 columns that support the ceiling, many of which are adorned with intricate carvings, including two with the head of Medusa. Visiting in late spring, you're likely to enjoy a quieter experience as tourists start to fill in the summer months. Inside, guests can explore the hauntingly beautiful waters while observing the serene fish swimming beneath the surface.