Hundreds of people surrounded St. Isaac's Cathedral amid competing protests over transferring the famed St. Petersburg building to the Russian Orthodox Church.
The February 12 protest was the latest to take place following last month's decision by city authorities to return the cathedral to church control.
It was seized by the state after the 1917 Bolshevik Revolution and became a museum. It's now a popular tourist destination.
Opponents of the transfer fear that, under church control, tours will emphasize the cathedral's religious aspects, at the expense of its cultural importance.
But supporters of the plan insist that the Orthodox Church is the rightful owner.
Opponents of the plan outnumbered supporters by a ratio of about two-to-one in the rival protests on February 12.