The Soviet "Los Alamos"
When the urban Kurchatov Institute in Moscow was ruled as unsuitable for the type of research and detonation testing needed for the Soviet bombs, the old monastery city of Sarov, located 250 miles east of Moscow, was chosen. Formerly a holy city, Sarov was now home to the newly constructed "forbidden city" of Arzamas-16. As far back as spring 1946, ten such secret atomic cities were built in the Soviet Union, and none of them appeared on any map.
Andrei Sakharov continued to oversee the superbomb development, and Yuli Khariton-known by many today as the father of the first Soviet nuclear bomb-was appointed scientific director at Sarov/Arzamas-16, which was sometimes referred to among the scientists as "Los Arzamas."