Castello di Rezzonico, Medieval castle in Rezzonico, Italy.

Castello di Rezzonico stands in Rezzonico, a hamlet of San Siro on Lake Como. It is a walled enclosure of about 2,000 square metres with a roughly trapezoidal plan, three towers and two entrances, built to shelter houses and the main tower rather than a single keep. Its high medieval tower carries Ghibelline merlons.

The castle was built by the counts Della Torre di Rezzonico during the 14th century, on a site where older fortifications probably stood. In the 16th century it was occasionally occupied by soldiers of Gian Giacomo Medici. The complex was restored in the 19th century.

The name Rezzonico comes from the Della Torre counts who built the castle in the 14th century. The high medieval tower is topped with Ghibelline merlons, the swallowtail crenellations that marked Guelph or Ghibelline allegiance in Lombardy. The walled enclosure held the village houses as well as the main tower.

The castle is located at Via Castello 48 in Santa Maria Rezzonico and easy to identify. The site sits in hilly terrain and is best explored on foot to take in the structure and surrounding landscape.

The castle replaced an earlier fortification of the village of Rezzonico. Its traces survive in a few fragments of the perimeter wall, in a 14th-century battlemented tower and in two entrance gates of the neighbouring built-up area.