That castle, a red-bricked structure built in the 14th century, and added to over various centuries to become a massive fortress with moats and all, was later modified yet again by Napoleon Bonaparte when he expelled the reigning Austrians and assumed the role of King over a temporarily unified Italy. During his reign, he removed the moats to the castle and commissioned the construction of the neoclassical triumphal arch known today as the Arco della Pace, or Arch of Peace.