Cavalieri was made one of the Convervatori in 1554, taking the position responsible for supervising construction at the Campidoglio that Michelangelo had begun restorating in 1538. Work on this complex project, involving the renovation of the existing Palazzo dei Conservatori and Palazzo Senatorio, as well as construction of a third building, the Palazzo Nuovo, did not begin until 1542 and would not be fully realized until 1662. Cavalieri was co-director for construction from 1554 to 1575 and supervised the project through its most productive phase of development. Despite his sharing responsibility for the construction with Prospero Boccapaduli, Cavalieri is mentioned to have been primarily responsible for the realization of Michelangelo's designs, while Boccapaduli managed the financial and administrative tasks.
