The Palazzo Ducale was built between 1775 and 1804 by Don Antonio Manca, Marquis de Mores and Lord of Usini, immediately after being given the title of Duke of Asinara. This structure is in the heart of the old town. 
The building has three floors: from the main entrance you enter the Great Hall with the detailed ceiling and sweeping staircases that lead to the noble quarters, where you can admire the many rooms, among them the old chapel and the meeting room which was originally a ballroom for the Duke’s receptions. 
The Palazzo from 1860 to 1878 became the headquarter of the Police force and then of the Provincial government. From 1878 it became the seat of the Municipality of Sassari, which purchased it in 1900.

Fonte: Sassati turismo