Milan: Sforza Castle.

“Sforza Castle was built in the 15th century by Francesco Sforza, Duke of Milan, on the remains of a 14th-century fortification. Later renovated and enlarged, in the 16th and 17th centuries it was one of the largest citadels in Europe. Largely remade by Luca Beltrami in 1891-1905, it now houses several of the city’s museums and art collections.”