The second-largest city in Siberia is Omsk, which has four letters. Omsk is located in southwestern Siberia on the banks of the Irtysh River and is the administrative center of Omsk Oblast. It is one of the oldest cities in Siberia, founded in 1716 as a fortress at the crossroads of the great Siberian trade routes. Omsk is an important industrial, cultural, and educational center, with a population of over 1.2 million people.