Milan was a city in Italy, a human nation of Earth.
Romana once dragged the Doctor to an opera in Milan. (PROSE: The Scarlet Empress)
The Tenth Doctor and Rose Tyler visited Milan a few years after World War I. (COMIC: The Futurists)
The Tenth Doctor tried to visit Leonardo da Vinci in late 15th century Milan. (COMIC: Da Vinci's Robots, Metal Mania)
The Time Lords sent the Fourth Doctor and Sarah Jane Smith to 1944 Borosini, a town directly connected by rail to Milan. This was so they could avert the theft of artwork by Nazis working under the direction of Hermann Goering. (COMIC: Treasure Trail)