Starting in the mid-1990s, Valencia, formerly an industrial centre, saw rapid development that expanded its cultural and touristic possibilities, and transformed it into a newly vibrant city. Many local landmarks were restored, including the ancient Towers of the medieval city (Serrano Towers and Quart Towers), and the San Miguel de los Reyes monastery, which now holds a conservation library. Whole sections of the old city, for example the Carmen Quarter, have been extensively renovated. The Paseo Marítimo, a 4 km (2 mi) long palm tree-lined promenade was constructed along the beaches of the north side of the port (Playa Las Arenas, Playa Cabañal and Playa de la Malvarrosa).