Rocca Pia, Medieval fortress in Tivoli, Italy.

Rocca Pia is a medieval fortress in central Tivoli featuring a square base with four towers of varying heights located near Piazza Garibaldi. The walls are constructed with thick stone and display typical defensive features of a 15th-century fortification.

Pope Pius II commissioned this fortress in 1461 as a tool to assert papal control over Tivoli and suppress potential local resistance. The construction reflected a broader effort to secure the Papal States in the territories surrounding Rome.

The fortress shapes Tivoli's downtown with its square form and four uneven towers that stand as a symbol of papal power in the medieval city. Visitors walking through Piazza Garibaldi encounter this structure as a reminder of how fortifications once controlled and protected urban life.

The fortress has been open to the public since 15 December 2018, managed by the Comune di Tivoli. Access is from the heart of the modern town, near Piazza Garibaldi. The interior courtyard and towers can now be visited, so allow time to walk the perimeter and look for the blocked drawbridge opening on the eastern side.

From the early 1800s until 1960 the structure served as a prison rather than a fortress, revealing how medieval military buildings were repurposed over time. This transformation illustrates the shift from defense to detention in the building's long history.