This is a Soviet poster celebrating 1st May, the international Worker’s Day. The flag says the famous “Workers of all countries, unite!” from the Communist Manifesto, and the caption below reports the next sentence, which is also famous: “The workers have nothing to lose but their chains, and the whole world to win”, under the text “1 May” and below the attribution (“K. Marx and F. Engels”). Finally, the text at the top says “Russian Socialist Federative Soviet Republic” (the official denomination of Russia within the Soviet Union).