St. Petersburg’s fascinating and conflicted history is evident in St. Isaac’s Cathedral, the fourth-largest cathedral in the world. Its design in 1818 by a French architect proved controversial, with a formal neoclassical plan and no onion domes or other Russian elements. After the Revolution, the church was stripped of all religious items and turned into a museum of religion and atheism. Today, services take place again. Throughout its history, secular and sacred, the monumental scale of the building has impressed visitors.