Basilica Cistern

Funny thing- my first time here I had a guided tour with Matt the marketing guy. Our guide took us to the two Basilica's and then to this tourist trap rug store where we saw "a cistern" (water reservoir). When the franchise group asked how we liked the basilica cistern we were like "eh- it was ok." and they were totally shocked that we weren't in AWE of the Cistern. Turns out, he did not take us to "THE BASILICA CISTERN" he took us to this mud pit under the furniture store. So, this trip I found the real one, and it was absolutely the best site outside the Hagia Sophia that I've ever seen. The Cistern is vast with over 300 columns which are lit with red lights which creates a surreal environment. At the far end of the cistern there are two Medusa Head's on the bast of the columns. There is a lot text about it online and in the guide books, but no real conclusion as to where they came from, or why they were used.