The original nucleus of the Castle most likely dates back to the 12th century, an era in which the San Martino di Agliè family began to dominate Canavese. Nowadays only a few mighty brick structures situated in the north-eastern area (underneath the current porter’s lodge) bear witness to the existence of the medieval fortification. The medieval Castle consisted of a residential building and an official building belonging to the San Martino family as well as a few farmhouses. The entire area was dominated by a high viewing and defence tower and it was surrounded by walls protected by a moat. This establishment remained unchanged until the mid 17th century.
Between 1646-1657 Filippo di San Martino, councillor of the ruling Maria Cristina di Francia, made the first fundamental transformation of the medieval country house into a residence.The plans, which are not documented, date back to Amedeo of Castellamonte, and they provided for a double window onto the park-garden and towards the town. There were also two large internal courtyards around which the apartments developed, connected by long galleries. There were high towers on the corners (called pavillons in French or pavilions) according to the layout referred to as “pavilion”. The front view towards the garden was identical to its current appearance, although the two towers were the same height (in the 19th century the south-westerly one was lowered by one floor). Nowadays, as was the case in the past, the garden has terracing at various levels, sustained by powerful support walls with niches animated by statues of fauna and mythological heroes.
During the Napoleonic occupation (1802-1814), part of the Castle was transformed into a poorhouse and gravely stripped of its most precious furnishings, which were sent off to France. The park-garden was sold to private investors and an access road to the town was built, which still divides the park from the garden today. Following the restoration, both the park and the garden were returned to Savoy ownership, but the road was by now an irreversible reality.
During the post-war period, a lengthy series of restoration and upgrading interventions took place to transform the Castle into a museum, as it appears today and to open it to the public. The craftsperson of this work was Umberto Chierici, Superintendent for the Monuments of Piedmont for almost thirty years. In 1986, after a complex botanical and plumbing restoration, the park and garden were opened to visitors.