Elizabeth was born at Kolomenskoye, near Moscow, Russia, on 18 December 1709 (O.S.). Her parents were Peter the Great, Tsar of Russia and Catherine. Catherine was the daughter of Samuel Skowroński, a subject of Grand Duchy of Lithuania. Although no documentary record exists, her parents were said to have married secretly at the Cathedral of the Holy Trinity in St. Petersburg at some point between 23 October and 1 December 1707. Their official marriage was at Saint Isaac's Cathedral in St. Petersburg on 9 February 1712. On this day, the two children previously born to the couple (Anna and Elizabeth) were legitimized by their father and given the title of Tsarevna ("princess") on 6 March 1711. Of the twelve children born to Peter and Catherine (five sons and seven daughters), only the sisters survived to adulthood. They had one older surviving sibling, crown prince Alexei Petrovich, who was Peter's son by his first wife, noblewoman Eudoxia Lopukhina.