Saint Isaac's Cathedral in Saint Petersburg, Russia is the largest cathedral in the city and was the largest church in Russia when it was built (101.5 meters high). It was dedicated to Saint Isaac of Dalmatia, a patron saint of Peter the Great who had been born on the feast day of that saint.

     The church on St Isaac's Square was ordered by Tsar Alexander I, to replace an earlier Rinaldiesque structure. A specially appointed commission examined several designs, including that of the French-born architect Auguste de Montferrand (1786–1858), who had studied in the atelier of Napoleon's designer, Charles Percier. Monferrand's design was criticised by some members of the commission for the dry and allegedly boring rhythm of its four identical pedimented octastyle porticos. It was also suggested that despite gigantic dimensions, the edifice would look squat and not very impressive. The emperor, who favoured the ponderous Empire style of architecture, had to step in and solve the dispute in Monferrand's favour.

     The cathedral took 40 years to construct, under Montferrand's direction, from 1818 to 1858. Under the Soviet government, the building was abandoned, then turned into a museum of atheism. The dove sculpture was removed, and replaced by a Foucault pendulum. During World War II, the dome was painted over in gray to avoid attracting attention from enemy aircraft. Worship activity has since resumed in the cathedral, but only in the left-hand side chapel, and in the main body of the cathedral on feast days only.

     The severe neoclassical exterior expresses a traditional Russian-Byzantine formula: a Greek-cross groundplan with a large central dome and four subsidiary domes. It is similar to Andrea Palladio's Villa La Rotonda, with a full dome on a high drum substituted for the Villa's low central saucer dome.

     The exterior, which barely hints at the riotously rich interior, is faced with gray and pink stone, and features a total of 112 red granite columns with Corinthian capitals, each hewn and erected as a single block: 48 at ground level, 24 on the rotunda of the uppermost dome, 8 on each of four side domes, and 2 framing each of four windows. The rotunda is encircled by a walkway accessible to tourists. 24 statues gaze down from the roof, and another 24 from the top of the rotunda.