Mariupol (Russian: Мариуполь) is a city in southern Ukraine, on the coast of the Sea of Azov. With a population of about 500,000, it is one of Ukraine's largest cities. It is a major Black Sea port. Originally a Cossack fortress, its importance grew due to its location as a warm water port. Founded after the Crimea had been taken from the Ottomans, Mariupol was part of the Russian Empire and USSR until 1991, when Ukraine gained independence. Today, it is mostly Russian-speaking and is close to the Russian border.