The places are officially known as "closed administrative-territorial formations" (закрытые административно-территориальные образования, zakrytye administrativno-territorial'nye obrazovaniya, or ЗАТО ZATO for short) in Russia and were called that in the former USSR.
There were 45 closed cities including some cities, such as Perm (tank factories), were opened well before the fall of the Soviet Union; others, such as Kaliningrad (major navel and radar base) and Vladivostok (major navel and radar base) remained closed until as late as 1992 and a few are still closed to this day.
To enter one needed a special permanent, called a Special Soviet travel pass card which covered people including workers, communist officials, KGB agents, long term local residents, close family members of workers and/or trusted traders who are not directly connected with its obscured and covert purposes.
The KGB and Ministry of the Interior Secret Police Force had cable taps, cameras, microphones, traffic sensors, monitors such as radio eavesdropping gear, sniffer dogs, and similar systems were require to spy on every one in both a undetected and unsuspecting manner.
- Mirny Diamond Mine
- Special Soviet travel pass card
- Ministry of the Interior Secret Police Force