The Catherine (She was Peter the Great's wife.) Palace is undoubtedly Tsarskoe Selo's top attraction, particularly renowned for the extraordinary Amber Room the original of which was stolen by the Nazi's during the Siege of Leningrad. You can tour the restored Amber Room here: http://www.youtube.com/watch?v=t_YTD7N8LS0&feature=player_embedded
In the 90s, Gayle invested in a treasure hunt that hoped to find the original somewhere in Eastern Europe using ground-penetrating radar. Never heard another word.