The city of Cheliabinsk, deep in the Russian Urals, was one of the closed cities of the Soviet Union to which all foreigners were denied entry. In the 1930s it housed a giant tractor factory, the heart of the modernisation of the backward Russian countryside; during the Second World War the factory was turned over to the mass production of Soviet medium and heavy tanks (which earned it the sobriquet ‘Tankograd’); after the war nearby townships hosted some of the vital new installations for the Soviet atomic programme. In a country notable for its fear of enemies, such a city was understandably out of bounds.

Lennart Samuelson is perhaps the world’s foremost expert on the Soviet military-industrial complex in the age of Stalin, but even he could not get into Cheliabinsk until it was finally opened up in 1992. He has used the opportunity of sudden and unexpected access to the city archives