Catherine Palace

This magnificent rococo-style Palace served as the summer residence of the Russian tsars.  It's impressive blue, white and gold facade is over 300-meter long.  Originally built by Rastrelli (who also designed St Petersburg's Winter Palace) in 1752, the palace suffered great damage during WWII (documented in photographs on display inside the building) and still undergoes repairs to this day.  Large sections of the palace are nonetheless open to the public, including the Great Hall, and the Amber Room.