Castello di Montesarchio, Medieval castle in Montesarchio, Italy.

Castello di Montesarchio stands on a hill above the town of Montesarchio, at the eastern end of the Caudina valley in Benevento province. The present building was mainly erected under Aragonese rule on the site of earlier Lombard and Norman fortifications. Visitors can still see the slots of the drawbridge and the protective moat.

The site on Monte Taburno held earlier fortifications, including Lombard and Norman occupations. The present structure was mainly built under Aragonese rule. After the Italian War of 1542-1546, it was confiscated and granted in 1532 to Alfonso II d'Avalos, Marquis of Vasto. In 1830 the kingdom turned it into a prison, which it remained until the end of the Second World War.

Since 2007 the castle has housed the Museo Archeologico Nazionale del Sannio Caudino. Its collection centres on finds from the Caudine Valley, including the Sannite and Caudine artefacts that give the museum its name. The former cells and courtyards of the prison period can still be seen, with inscriptions left on the walls by jailed patriots.

The site is accessible via walking paths from the town center, and guided tours are available for those who want more detailed information. Wear sturdy footwear as the path to the summit is steep and the ground can be uneven.

In the mid-19th century, the fortress served as a prison for Italian political detainees, including well-known patriots fighting for independence. This dark chapter is often overlooked by visitors who focus on its medieval past.