Cuasso Castle, Medieval castle in Cuasso al Monte, Italy

Cuasso Castle is a medieval stronghold in Cuasso al Monte in northern Italy, built on a hilltop with sections containing Roman-era remains. The structure reveals multiple construction phases through its masonry and layout.

The oldest tower dates to Roman times, when it served as a signalling post; the Lombards enlarged it in an unusual plan comparable only to Warkworth Castle and the lost castle of Trecate. The castle guarded the road from Milan to the San Bernardino and Gotthard passes before the Melide bridge existed, and later belonged to the Contado del Seprio. It was abandoned by the 13th century, housed the parish until the mid-16th century, then became a cemetery.

Locals call the castle Castelasc in the Lombard dialect. The name Cuasso probably blends the Latin covum (cove) with the Germanic Sachs-i (Saxon sword), a late Latin form of Saxo. The Lombards settled conquered land by family groups called farae, and this practice left traces in local place names.

The north-east fortress, the oldest part at 455 m, is reached only with difficulty because of the slope and thick vegetation, while the keep stands at 430 m. The main cartway door on the south-east wall was entered over a raised wooden walkway. Sturdy footwear is needed on the uneven ruins.

The north-east fortress, the castle's oldest part, began as a Roman signalling tower and was enlarged by the Lombards. From that hilltop, unlike from the mastio, the whole southern area of Lake Lugano is visible. Its access remains difficult because of the relief and thick vegetation.