Built around 220AD, Hadrian's Villa used to be a retreat for Roman Emperor Hadrian, while today it is a registered UNESCO World Heritage Site that showcases the Roman empire's propensity for lavishness. The villa covers an area of 120 hectares, which is about 100 city blocks in New York! Needless to say, no expense was spared in the construction of this haven just 28km away from Rome. Even Emperor Hadrian preferred living in the villa more so than his palace on Palatine Hill and eventually stayed there permanently towards the end of his reign.