Saint Isaac's Cathedral
He took Martha Skavronskaya, a Polish-Lithuanian peasant, as a mistress some time between 1702 and 1704. Martha converted to the Russian Orthodox Church and took the name Catherine. Though no record exists, Catherine and Peter are described as having married secretly between 23 Oct and 1 December 1707 in St. Petersburg. Peter valued Catherine and married her again (this time officially) at Saint Isaac's Cathedral in Saint Petersburg on 19 February 1712.