Once emperor Massimiano made Milan the capital city of his empire, he needed an imperial palace. Most of the western portion of the city was thus devoted to the building, which included a direct entrance to the circus, apartments for his family, tombs and gardens.
New parts of this residence are still being discovered, most recently during the construction of one of the metro stations on the new M4 line.
Nowadays you can only admire the foundations and mosaics of the once majestic imperial palace, but those alone can give you a vague idea of the wealth and relevance of the city. If you'd like to step into Massimiano's shoes for an afternoon and contemplate the beauty and greatness of these ancient buildings, you should definitely pick this tour!