Castello di Giulio II

Near the former mouth of the Tiber at Ostia, the Castle of Julius II is a Renaissance fortress built to guard Rome's river entrance. Its three towers and gunpowder-era casemates surround a broad moat; the monumental stairway retains frescoes of Hercules.

Why it matters

Construction began in 1483 on the order of Cardinal Giuliano della Rovere, the future Pope Julius II. Florentine architect Baccio Pontelli designed the fortress, built during the 1480s. Its triangular arrangement of towers and casemates reflects the transition toward artillery-based defence. One tower incorporates an earlier structure built under Pope Martin V in the early fifteenth century.

What to notice

The fortification's casemates were built for firearms. The main tower encloses the older Martin V tower, preserving an earlier layer of the site. On the monumental staircase, frescoes of Hercules are attributed to the school of Baldassarre Peruzzi. The courtyard well bears the Rovere arms.

Context and history

The castle was built to control the Tiber mouth, river traffic and the salt trade. A siege in 1556 and a major flood in 1557 marked the end of its military role; the flood changed the river's course and left the fortress inland. The castle later served as a papal prison, and prisoners were put to work on archaeological excavations at Ostia under Pius VII and Pius IX. Restoration campaigns continue to shape the building's modern history.