Fortezza del Cerruglio, Medieval fortress in Montecarlo, Italy.

Fortezza del Cerruglio is a medieval fortress in Montecarlo with a triangular shape featuring a semi-circular tower and two square towers linked by thick defensive walls built from squared stone blocks. This structure shows how military builders of the time combined different tower shapes to create a strong and flexible defense system.

The first fortifications on the hill date to the 12th century; the oldest surviving part is a massive semi-circular stone keep with the Lucca coat of arms, reached by a retractable ladder. Castruccio Castracani enlarged it with two square towers and curtain walls, and from here his troops left for the Battle of Altopascio in 1325. In 1331 Giovanni of Bohemia and his son Charles founded the walled village of Mons Karoli beside it.

The name Cerruglio comes from the oldest fortifications on the hill. Since 1775 the fortress has been private property, restored by its owners and opened in summer, when the restored halls and courtyards host exhibitions and cultural events. The garden between the Medici bastions and the old keep, once the parade ground, has box hedges, orange and lemon trees, old roses and acanthus.

The fortress opens during summer months for exhibitions and guided tours, so it is best to check in advance for specific opening times. The site is easily reached on foot, and visitors should wear sturdy shoes since the uneven walkways and stairs require careful footing.

The three surviving gates belong to the village wall, not the fortress: the Porta Fiorentina, the small Porta a Lucca from the 14th century and the 16th-century Porta Nuova. The wall had fifteen towers grafted onto the fortress; some towers are still visible.