Modena is located 34 metres above sea level and very little remains of the topography of the Roman city, replaced, during the middle ages and the Renaissance, by a ring structure, with narrow streets in porches, pentagonal fortifications, erected in the 15th century, they did place in gardens and boulevards, which developed the new districts. The oldest has a rich artistic heritage: the Romanesque cathedral (11th-13th centuries) with the famous Torre della Ghirlandina (87 meters), the Doge's Palace (17th century), now the seat of the Military Academy, the Estense Gallery, the churches of San Pietro (XV-XVI), of St. John the Baptist, St. Mary's Pompous, both of the 18th century, the Palace of the University. The Cathedral, Torre Civica (Ghirlandina) and Piazza Grande in the city have been declared World Heritage site by UNESCO.