The castle originated from a fortified building that was erected in the 13th century next to the city's walls. This first building was called Castelvecchio (literally, 'old castle'), and was the seat of the Bishop of Trento from the 13th century onwards to the end of the 18th century.

The castle is composed of a series of buildings of different eras, enclosed by a circle of walls in a slightly elevated position above the town. The, as called, Castelvecchio is the oldest and most dominant building of the entire housing development. The Magno Palazzo is the sixteenth expansion in the forms of the Italian Renaisance, wanted by the Prince Bishop and Cardinal Bernado Clesio (1485–1539), the third part, in the southern end of the complex is the known Eagle tower, which preserves the famous Cycle of the Months, one of the most fascinating pictorial cycles of profane Middle Ages.

Courtesy of Wikipedia