Rijeka is the principal seaport of Croatia, and the third-largest city in the country (after Zagreb and Split). It is located on Kvarner Bay, an inlet of the Adriatic Sea. Historically, because of its strategic position and its excellent deep-water port, the city was fiercely contested, especially among Italy, Hungary, Austria-Hungary, and Yugoslavia, changing hands and demographics many times over the centuries. There were brief periods of time when it was an independent city-state, most recently 1920-1924 following the Treaty of Trianon.
Prior to the 20th century, Rijeka was known internationally by its Italian name Fiume. Both Rijeka and Fiume translate as River, reflecting the city's original name "River of Saint Vitus," given during the Roman Empire.