Red Square. The Kremlin.
A long line is formed to enter Lenin's Tomb (Mausoleum) at left. The Fun Palace is on the other side of the wall, St. Nicholas (Nikolskaya) Tower in the center, Arsenal building behind, Corner Arsenal (Uglovaya Arsenalnaya) Tower to its right, State Historical Museum on the far right.
Taken by my grandfather David C. Cook on a visit to Moscow for a meeting of the International Electrotechnical Commission. Development stamp is June, 1969, so perhaps this is May.