The USSR was formed out of the ashes of the Russian Revolution. Vladimir Lenin, the creator and first leader of the Union, had denounced Tsarist Russia for holding Russians and non-Russians in a “prison of nations.” His aim was to unite the masses of the lands once exploited by the Tsar into a country that was “national in form, socialist in content.”
Thus on December 30th, 1922, five years after the end of the Tsarist Empire, the USSR was born, with Moscow as the capital.
It was the largest country in the world, occupying nearly one sixth of the earth’s land surface and housing more that 100 distinct nationalities.  It spanned from the Baltic and Black seas to the Pacific Ocean consisted of 15 Soviet Socialist Republics, namely Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan.