Photos

View of the mosaics in the Church of the Savior on Spilled Blood. Due to the crowd of tourists, mainly Russian, it was difficult to photograph the walls, so I shot the ceiling, equally beautiful. No flash! It is not as beautiful as in reality...

From Wikipedia:

The Church of the Savior on Spilled Blood (Храм Спаса на Крови) is one of the main Russian Orthodox churches of St. Petersburg, Russia. It is also variously called the Church on Spilt Blood and the Cathedral of the Resurrection of Christ (Собор Воскресения Христова), its official name. The name refers to the blood of the assassinated Alexander II of Russia, who was mortally wounded on that site on March 13, 1881 (Julian date: March 1).
Architecturally, the Cathedral differs from St. Petersburg's other structures. The city's architecture is predominantly Baroque and Neoclassical, but the Savior on Blood harks back to medieval Russian architecture in the spirit of romantic nationalism. It intentionally resembles the 17th-century Yaroslavl churches and the celebrated St. Basil's Cathedral in Moscow. The Church contains over 7500 square metres of mosaics -- according to its restorers, more than any other church in the world. This record may be surpassed by the Cathedral Basilica of St. Louis, which houses 7700 square meters of mosaics.
Frescoes and mosaics in the interior.
Frescoes and mosaics in the interior.

The interior was designed by some of the most celebrated Russian artists of the day - including Viktor Vasnetsov, Mikhail Nesterov and Mikhail Vrubel - but the church's chief architect, Alfred Alexandrovich Parland, was relatively little-known (and Russian, despite his name). Perhaps not surprisingly, the Church's construction ran well over budget, having been estimated at 3.6 million roubles but ending up costing over 4.6 million. The walls and ceilings inside the Church are completely covered in intricately detailed mosaics - the main pictures being biblical scenes or figures - but with very fine patterned borders setting off each picture.