Since the breakup of the Soviet Union almost 25 years ago, the face of Russia's capital has changed dramatically as investment and growth led to a flood of construction and many historic buildings were left to rot or torn down. But while Moscow's Stalinist skyscrapers are protected as icons, Russian activists say the Soviet Union's avant-garde architecture of the 1920s, which once had global influence, is at risk of disappearing. VOA's Daniel Schearf reports from Moscow.