Novosibirsk is the third most populous city in Russia after Moscow and St. Petersburg and the most populous city in Asian Russia, with a population of 1,523,801. It is the administrative center of Novosibirsk Oblast as well as of the Siberian Federal District. The city is located in the southwestern part of Siberia on the banks of the Ob River adjacent to the Ob River Valley, near the large water reservoir formed by the dam of the Novosibirsk Hydro Power Plant. and occupies an area of 502.1 square kilometers. The city is informally known as the "Capital of Siberia".