For mail delivery, a closed city is usually named as the nearest large city and a special postcode e.g. Arzamas‑16, Chelyabinsk‑65. 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 the 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.[1] To relocate to a closed city, one would need security clearance by the organization running it, such as the KGB in Soviet closed cities.