Forte Michelangelo, Civitavecchia, Roma (1508-1535)

The fort was commissioned by Pope Julius II (1443-1513) to the Renaissance architect Donato Bramante (1444-1514) to defend the port against pirate incursions. The structure was finished by Bramante's pupils Giulio Leno and Antonio Sangallo the Younger. It is believed that the taller octogonal tower (Maschio) was added by Michelangelo later. 

Despite the participation of several famous Renaissance architects, Forte Michelangelo is still a traditional medieval fortification with round towers that have blind spots. (Georgiana Hedesan)