Omsk is the administrative center and largest city of Omsk Oblast, Russia. It is situated in southwestern Siberia and has a population of over 1.1 million. Omsk is the third largest city in Siberia after Novosibirsk and Krasnoyarsk, and the twelfth-largest city in Russia. It is an important transport node, serving as a train station for the Trans-Siberian Railway and as a staging post for the Irtysh River.

Omsk Oblast is a federal subject of Russia, located in southwestern Siberia. The oblast has an area of 139,700 square kilometers (53,900 sq mi). Its population is 1,977,665 with the majority, 1.12 million, living in Omsk, the administrative center.