In the 13th century, many towers were taken down or demolished, and others simply collapsed. Many towers have subsequently been utilized in one way or the other: as prison, city tower, shop or residential building. Still, the towers remained a famous sight of Bologna throughout the later periods; even Dante mentioned some of the towers in his "Inferno". The last demolitions took place during the 20th century, according to an ambitious, but retrospectively unfortunate, restructuring plan for the city; the Artenisi Tower and the Riccadonna Tower at the "Mercato di mezzo" were demolished in 1917.