Palazzo dei Conservatori
The Palazzo dei Conservatori formerly was seat of the magistrates administrating the Rome during the Papal rule, while currently it houses the Capitoline Museums.
History
One of the structures that comprises the Campidoglio, this Palazzo served as the seat of the Roman magistrate responsible for administrating the city. By the end of the 15th century, they had very little actual power, the Pope ran the city from the Vatican.
In the mid-16th century, Michelangelo got his hands on the building, re-designing the facade and adding gigantic Corinthian pilaster strips on high pedestals to make it a little less ostentatious.