Basilica Cistern (Yerebatan Sarayı) (Istanbul)

About two thirds of the original structure are accessible though as other parts of Basilica Cistern were bricked up in the 19th century. When Turkish forces stormed into medieval Constantinople they overlooked existence of underground structure. It became evident the local Greeks were hiding something when Turkish forces saw locals draw water and reportedly even fish from their basements. Upon closed expansion they realised that there was much bigger structure underneath people's private homes.

Even today as you walk through these underground structure you can't help by wonder how much work was put into this immense structure. Basilica Cistern is accessible by a wooden walkway that zigzags through a cistern. Quiet music is playing in the background while you explore this man made cave. If you look up to the ceiling you can see where local Greeks used to collect water and even catch fish that was probably transported here by mistake via an aqueduct. Hundreds of carps were reintroduced to the Basilica Cistern to keep historic accuracy.

Many of the columns that were gathered here were taken from various places around the city. At least two towers have peacock feather pattern along its length. It is certain that these columns were looted from the destroyed arch of Theodosius the Great. Additionally in the end of the walkway you can see two huge boulders shaped into heads of legendary Medusa Gorgon. According to Ancient Greek pagan mythology she was an evil woman who had snakes for hair and she could turn all mortals into stone with a glance. It is possible that two heads of Medusa were taken from some destroyed pagan temple after it was destroyed by the Byzantine Emperors to make way for new structures. Part of the columns and stone work were simply used in the Basilica Cistern.