Rocca di Monfalcone, Medieval fortress in Monfalcone, Italy.

Rocca di Monfalcone is a late-antique fortress on a hill behind the town, first built around 490 under Theoderic the Great. Its walls were repaired and given a parapet in the 15th century, and in the 16th century a square stone tower for storing gunpowder was built at the centre. The hilltop now holds a speleological museum.

The hilltop was occupied in prehistory, and remains of a prehistoric castelliere are still visible. Around 490 Theoderic, king of the Ostrogoths, is held to have built the fortress after defeating Odoacer on the Isonzo. In 967 Otto I granted Monfalcone and the rocca to the Patriarchate of Aquileia; the fortress is first named in documents in 1289. It passed to the Counts of Gorizia in 1409 and to Venice in 1420.

The name "Verruca Montis Falconis" (summit of Monte Falcone) was later shortened to "rocca". Since 1968 the hilltop has been entrusted to the Gruppo Speleologico Monfalconese "Amici del Fante", founded in 1948, which runs the speleological museum there and organises guided school visits on Karst phenomena.

The hilltop is reached on foot; the museum's permanent speleological display sits on the summit, while its offices and laboratories are in town at Via Valentinis 134. The site was restored between 1950 and 1955 and has been managed since 1968 by the Gruppo Speleologico Monfalconese "Amici del Fante".

The square stone tower at the centre was built after 1525 on the initiative of podestà Giovanni Diedo, who had the fortress rebuilt from its foundations to withstand firearms and used the tower to store gunpowder. A carved stone plaque above the tower door records the return of the Rocca to Venetian hands.