Moscow's city government has pre-approved construction of the world's largest building, "Crystal Island", which at 27 million square feet will essentially be a city within a city. The project is estimated to cost 4 billion dollars and should be finished by 2013.
As a frequent visitor to the Russian capital I can't imagine this being part of the cityscape, it just doesn't fit in. My feeling is that Crystal Island is a modern day version of the thankfully never built "Place of the Soviets" except now its a monument to capitalism... it even looks like the BP logo when viewed from the top :)
Here are some pictures of the project designed by Sir Norman Foster: