 In Rome itself, encastellation often led to the fortifying of the ancient monuments which had fallen into disuses, such as the Arch of Constantine and the Colosseum.These fortresses were usually in the hands of one of the powerful lay families, but sometimes of the popes.In the Mezzogiorno, the independent principalities of the Lombards and the Greek city-states, which distanced themselves from any central authority, formed an opportune place for the proliferation of castles.