The holiday marks the adoption on June 12, 1990 of a Declaration of Independence by lawmakers. It was declared a holiday in 1994 by President Boris Yeltsin and was known for nearly a decade as Independence Day.
President Vladimir Putin presented state awards to Russians recognized for achievements in science, literature, and the arts at a ceremony in the Kremlin broadcast live on television.
Some 200,000 police officers are out in the streets to enforce law and order.
According to a recent opinion poll, more than half of Russians view June 12 simply as a day off.