Castle of Serravalle, Medieval castle on a hill in Bosa, Italy

The Castle of Serravalle is a medieval fortress on the hill of Serravalle above Bosa, in northwestern Sardinia. Its 352-metre wall circuit encloses the whole plateau (about one hectare) and is punctuated by seven towers; the inner stronghold covers about 2,000 square metres. The walls are of greyish-brown masonry, with a square flat-topped tower at the left end and a taller square keep near the right, beside a slightly lower tower.

The Malaspina family, originally from Tuscany, had the fortress built in the 13th century to control this part of Sardinia. In later centuries the site changed hands and was altered several times to keep up with new military needs.

The castle's palatine chapel, Nostra Signora de Sos Regnos Altos, stands in the place-of-arms and holds a cycle of 14th-century frescoes. The name, in Sardinian, means Our Lady of the High Kingdoms. In 1980 Poste Italiane issued a 450-lira stamp showing the castle in its Castelli d'Italia series.

Getting to the castle means climbing a stone staircase from the town center, so sturdy shoes are a good idea. The site is generally open every day, and visiting in the morning or late afternoon makes the climb more comfortable.

Excavations at the site showed that the fortress was built around 50 years later than written records had suggested. This finding is a good example of how physical evidence can change what historians believed about a place.