Founded in 1716 as a fortress on the Imperial Russia's expanding southern frontier, by 1850s, Omsk grew to become the capital of Western Siberia and parts of Central Asia. The construction of the Trans-Siberian Railway in the late 1890s brought a rapid development boom, culminating in an extravagant 1910s World Fair, around the time of which Omsk acquired much of its neoclassical architectural heritage. Largely due to its strategic importance as the gateway to Siberia and the Russian Far East, Admiral Kolchak of the anti-Soviet White Army chose Omsk as his base and "capital of Russia" in 1918–1919.