Catania is the second largest city of Sicily after Palermo located on the east coast facing the Ionian Sea. It is the capital of the Metropolitan City of Catania, one of the ten biggest cities in Italy, and the seventh largest metropolitan area in Italy. The population of the city proper is 320,000 while the population of the city's metropolitan area, Metropolitan City of Catania, stood at 1,116,168 inhabitants. Standing almost entirely on the lava left by various eruptions, the city slopes slightly downward from north to south. The use of volcanic tufa for building has given the older part of the city its prevailing dark-gray colour. Almost completely rebuilt after the 1693 earthquake, the centre of the city has a distinctly 18th-century appearance. Ancient remains include the ruins of Greek and Roman theatres, and a Roman amphitheatre, basilica, baths, and aqueducts. The Ursino Castle with its four angular towers, constructed (1239–50) for Frederick II, long served as a model of military architecture. It now houses the civic museum with rich collections of art and archaeological relics. The centre of modern civic life is the Duomo Piazza, surrounded by 18th-century palaces and opening onto wide streets. Of the original structure of the cathedral founded by the Norman count Roger I in 1091, three apses of dark lava and part of the transept remain. After the 1693 earthquake it was rebuilt by the architects Fra Fiolamo Palazotto and Giovanni Battista Vaccarini (1702–68). The cathedral contains relics of St. Agatha and the tomb of the composer Vincenzo Bellini, a native of Catania. The Church of San Nicolo (1693–1735), the largest in Sicily, is connected with the former Benedictine monastery of the same name; it was begun in the 14th century and completed in the 17th century. The university, the first in Sicily, was founded in 1434 by Alfonso of Aragon, and its library (1755) possesses a number of important medieval manuscripts. Other notable landmarks include the Baroque Church of Santa Agata, the town hall by Vaccarini, the elephant fountain (1736) in the Duomo Piazza, the Collegiata (or royal chapel), the astronomical observatory, and the birthplace of Vincenzo Bellini, now a museum. Modern Catania, the second largest city in Sicily, is an industrial and transportation centre, connected by rail with Palermo, Messina, and Syracuse, with one of the busiest ports in Italy. Industries include a variety of mechanical and chemical manufactures, food processing, and fishing. About half of Sicily’s refined sulfur comes from the factories of Catania. The marketing centre for the surrounding agricultural region, it exports almonds and oranges, as well as handwork in metal, wood, and amber. It is also a popular winter resort with fine beaches nearby.