Dating back to 532 AD, the Basilica Cistern is the city's largest covered cistern, originally supplying water to the Great Palace, home to emperors. Walk along the raised platforms and soak up the sights while standing safe and dry among 336 illuminated marble and granite columns. See the Byzantine architecture and the famous Medusa heads at the base of the columns. This historic site has appeared in films like Dan Brown's "Inferno" and the James Bond movie.