Closed city
A closed city or town is a settlement where travel or residency restrictions are applied so that specific authorization is required to visit or remain overnight.
[citation needed] There may also be a wider variety of permanent residents, including close family members of workers or trusted traders who are not directly connected with clandestine purposes.
In modern Russia, such places are officially known as "closed administrative-territorial formations" (Russian: закрытые административно-территориальные образования [ЗАТО], romanized: zakrytye administrativno-territorial'nye obrazovaniya [ZATO]).
[1] In some cases, there may be no road signs or directions to closed cities, and they are usually omitted from railroad timetables and bus routes.
The actual settlement can be rather distant from its namesakes; for instance, Sarov, designated Arzamas-16, is in the federal republic of Mordovia, whereas Arzamas is in Nizhny Novgorod Oblast (roughly 75 kilometres (47 mi) away).
People not living in a closed city were subject to document checks and security checkpoints, and explicit permission was required for them to visit.
They were built close to rivers and lakes that were used to provide the large amounts of water needed for heavy industry and nuclear technology.
They had to have special permission to travel there or leave, and anyone seeking residency was required to undergo vetting by the NKVD and its successor agencies.
Access to some closed cities was physically enforced by surrounding them with barbed wire fences monitored by armed guards.
"Mailbox" (Russian: Почтовый ящик, romanized: Pochtovyy yashchik) was the unofficial name of a secret Soviet facility much like the closed city, but smaller, usually the size of a factory.
However, on 30 October 2001, foreign travel was restricted without exception in the northern cities of Norilsk, Talnakh, Kayerkan, Dudinka, and Igarka.
The village, on the left bank of the Dniester river, contains a large Soviet-era ammunition depot guarded by Russian troops.
Following several stages of reduction, by 2016, the border town of Sha Tau Kok remained as the sole settlement within the FCA.
The Yongbyon Nuclear Scientific Research Center sits within a closed city that occupies 24.8 square kilometers (9.6 sq mi).
