Rocca di Ripafratta, Medieval fortress in San Giuliano Terme, Italy.

Rocca di Ripafratta is a medieval fortress built on Vergario hill with an irregular polygon structure anchored by three towers. The walls are constructed from small squared limestone blocks and display multiple building phases from different periods.

A tower stood on Vergario hill by 970; the Da Ripafratta family built the castle around it to levy tolls on road and river traffic, prompting Lucca's war in 1104. Pisa helped recover it, and in 1109 the family donated part of the castle to Pisa's archbishop Pietro Moriconi. In 1162-1164 Pisa enlarged it into a castle with a concentric wall around the village. After Pisa's 1254 defeat at San Savino it passed to Florence, then to Lucca, before Pisan troops retook it on 24 September 1261.

The fortress is also called Rocca di San Paolino, after Lucca's patron saint, a name reflecting the Da Ripafratta family's early ties to the Lucca bishopric. The family built the castle to levy tolls on road and river traffic, and those duties sparked the 1104 war with Lucca. Two watchtowers, Niccolai and Centìno, still stand on the surrounding hills.

The site is reached on foot from Ripafratta, a hamlet of San Giuliano Terme on the Pisa-Lucca border along the SRT12 road. The ruins stand on the Vergario hill above the village, and the surrounding slopes hold the Torre Niccolai and Torre Centìno, which can be spotted from the paths.

Excavations in the 1980s uncovered ancient Iron Age structures buried beneath the fortress foundations. These early discoveries reveal the site was inhabited long before medieval times.