Rijeka, also known as Fiume, is the principal seaport and the third-largest city in Croatia. It is located in Primorje-Gorski Kotar County on Kvarner Bay, an inlet of the Adriatic Sea and in 2021 had a population of 108,622 inhabitants. Historically, because of its strategic position and its excellent deep-water port, the city was fiercely contested, especially between the Holy Roman Empire, Italy and Croatia, changing rulers and demographics many times over centuries.