"This imposing castle built by Pope Pius II in 1461 was used as a prison until the 1960s. The inside is closed to the public, so most people just stop by to snap some photos on their way to the Villa d'Este or Villa Adriana. Seeing this medieval landmark is a good reminder that Tivoli—like Rome—is a potpourri of architectural styles due to its long history." - Laura Itzkowitz, Arlene Gibbs