One public housing flat in Moscow stood out above all others: the home of George Costakis, the foremost collector of early 20th century Russian avant-garde art. Its walls were crowded with banned and forgotten works by artists such as Malevich, Tatlin, Kandinsky, Chagall, Lissitzky, Rodchenko, and Kliun; public figures such as Edward Kennedy, Stravinsky, and Alfred Barr visited. Barrie Gavin met the collector in 1982 at his home in Athens. Costakis, a Greek born in Russia, passionately shares hi...