Rostov-on-Don is the largest city in South Russia and the centre of Russia's Southern Federal District. Although officially known as Rostov-on-Don to distinguish it from the ancient city of Rostov, in speech it is usually just called Rostov as the bigger of the two Rostovs (the orginal Rostov is confusingly then often called Rostov-Veliky). Rostov-on-Don is closely associated with the Cossacks and is also referred to as the 'Gateway to the Caucasus'. In 2018 the city served as a FIFA World Cup venue.