Spain has many historical monuments and buildings, including the Guggenheim museum in Bilbao, the Oceanographic in Valencia, and the Alhambra in Granada. Some of the most important cities are Barcelona, Seville, and Madrid. Roman ruins still stand, such as the amphitheater in Mérida and the Cornalvo Dam built during the Roman era. Spanish culture is expressed through important national celebrations like Holy Week in Seville and local cuisine that varies by region.