In 1830, Thon completed his most ambitious design to date, that of the Cathedral of Christ the Saviour in Moscow. The Russian-Byzantine Revival style of his project, intended to underline similarity of the new church with old cathedrals of the Moscow Kremlin, displeased many of his fellows, who wanted to see the cathedral built in the severe Neoclassical style. Nevertheless, the emperor personally approved his design. Thon and his disciples continued to work on the cathedral for the next 50 years, until the master's death in 1881.