The architecture of Provence includes a rich collection of monuments from the Roman era, Cistercian monasteries from the Romanesque period, medieval castles and fortifications, as well as numerous hilltop villages and fine churches. Provence was a very poor region after the 18th century, but in the 20th century it had an economic revival and became the site of one of the most influential buildings of the 20th century, the Unité d'Habitation of the architect Le Corbusier in Marseille.