Barnaul is the largest city and administrative centre of Altai Krai, Russia, located at the confluence of the Barnaulka and Ob Rivers in the West Siberian Plain. As of the 2021 census, its population was 630,877, making it the 20th-largest city in Russia and the fourth-largest in the Siberian Federal District. Located in the south of western Siberia on the left bank of the Ob River, Barnaul is a major transport, industrial, cultural, medical and educational hub of Siberia.