The Church of the Savior on Spilled Blood is the photograph of St Petersburg you have already seen: onion domes in patterned tile, polychrome facades, and gilded crosses rising over the Griboedov Canal at the spot where Tsar Alexander II was assassinated. Built between 1883 and 1907 in a deliberately Russian Revival style — a defiance of the European baroque and neoclassicism that dominate the rest of the city — it looks much closer to the cathedrals of Moscow's Red Square than to anything else in St Petersburg.
The interior is mostly mosaic — more than 7,000 square metres of it, covering every wall and ceiling. The result is overwhelming on first sight: dense, glittering, biblical, exhausting. Allow an hour to take it in properly. The entrance is on the canal side, with audio guides available, and queues are long in summer. The church is no longer consecrated and is run as a museum under the Cathedral of St Isaac's administration.