Detaining dangerous prisoners, keeping secrets of pristine information or ancient treasures priceless, these locations are closely monitored, to a cockroach also difficult to pass.
Terre Haute, Indiana, USA: This is where America's most dangerous criminals are kept. This prison was designed, operated and monitored to the extent that it was used as a model for Guantanamo detention. Terre Haute has two special areas that hold prisoners of death and prisoners of limited exposure (usually terrorist criminals).
The most imprisonment in the prison was supervised remotely (at a center in West Virginia). The civilians were never allowed to enter the prison (except lawyers) and any visit was closely monitored and carried out in a glass-enclosed room. If Andy Dufresne was detained here instead of Shawshank, he would never see the sun again.
Iron Mountain Depot, Butler County, Pennsylvania, USA: Built on an old mine, Iron Mountain Warehouse is where the company of the same name stores the items according to customer requirements. This huge underground bunker contains millions of paintings, original footage, documents, books, etc. This place has 24/7 security guard, with state-of-the-art surveillance system.
Forbidden City, China: You may think the Forbidden City today is no secret when it welcomes millions of tourists every year. However, visitors are only allowed to visit public areas. The Forbidden City contains countless well-kept secret rooms, where priceless treasures are kept. In addition, an army of 180 cats to help control the number of mice here effectively.
Guantanamo Bay, USA: This prison is located in the US military base of Guantanamo Bay. This place imprisons dangerous prisoners with strict surveillance system and many forms of confidential guard. The US hires this Cuba area under a treaty that can only be torn down when both sides agree - which is perhaps far from happening.
Pionen White Mountains Data Center, Stockholm, Sweden: Wikileaks servers are located at a depth of 30 meters deep at the foot of White Mountain in Stockholm. The Pionen White Mountains data center belongs to the network service provider Bahnhof - a company that values the privacy of its customers. This bunker was built in 1943 and was renovated during the Cold War to provide shelter for the government. In addition to anti-bomb design, 45 cm thick iron doors, submarine-powered backup generators, 24/7 security guards.