This is Saint Isaac's Cathedral in Saint Petersburg. It's the largest Russian Orthodox cathedral in the city and fourth largest in the world.
Here's a shot of the iconostasis, the wall of icons and religious figures that separates the nave from the sanctuary. The six columns are carved from malachite and the two smaller blue ones, from lazurite.
One interesting fact that I read ... the structure rests on 10,000 tree trunks that were sunk by a large number of workers into marshy fields to keep it stable.
Saint Petersburg, Russia
Saint PetersburgRussiaRussianOrthodoxCathedralChurchReligioncolorfulBalticornatecolumnsMarcusRichard Marcustravel photography