Lazio is a central Italian region bordering the Tyrrhenian Sea. Its principal city, Rome, is Italy’s capital and was at the heart of the ancient Roman Empire. Its iconic ruins include the Coliseum, an amphitheater that seated thousands. On the coast, the ancient port of Ostia still retains detailed mosaics and a theater. Inland are the forested Apennine Mountains, with nature reserves, lakes and stone-built villages.