I think Lonely Planet can describe the Cathedral best:
This gargantuan cathedral was completed in 1997 – just in time to celebrate Moscow’s 850th birthday. It is amazingly opulent, garishly grandiose and truly historic. The cathedral’s sheer size and splendour guarantee its role as a love-it-or-hate-it landmark. Considering Stalin’s plan for this site (a Palace of Soviets topped with a 100m statue of Lenin), Muscovites should at least be grateful they can admire the shiny domes of a church instead of the shiny dome of Ilyich’s head.
The Cathedral of Christ the Saviour sits on the site of an earlier and similar church of the same name, built in the 19th century to commemorate Russia’s victory over Napoleon. The original was destroyed in 1931, during Stalin’s orgy of explosive secularism. His plan to replace the church with a 315m-high Palace of Soviets never got off the ground – literally. Instead, for 50 years the site served another important purpose: the world’s largest swimming pool.