Apparently if you're in a city that a lot of people like to invade for its strategic value, you going to have a lot of sieges. And what do you need if you can't go on the other side of the wall...water. So pretty much everyone who has taken over Istanbul has installed a cistern to hold water within the city gates - and the largest one is the Basilica Cistern which is in the heart of the old city.Total capacity of the cistern would have been 80,000 cubic square meters - that's a lot. Maybe a better idea on how big the place was . . . 143 meters by 65 meters (oh come on people, learn the metric system...95% of the rest of the World has).
And I did not learn this until after I was back Wikipedia-ing...this was also the site of a scene in the James Bond flick 'From Russia With Love'.
