1. ADMAX Florence Prison

The US Penitentiary, Administrative Maximum Facility (USP Florence ADMAX) is an American federal prison in Florence, Colorado. This prison was opened in 1994, providing a higher level of custody than a maximum-security prison. The prison houses the most dangerous criminals in the US state of Colorado. For the extremely tight security measures, including attack dogs, 12ft high razor-wire fences, motion-detecting laser beams, ADMAX earned the nickname "Alcatraz of the Rockies".

2. The Granite Mountain Records Vaults

The Mormon Church's Granite Mountain Records Vault, also known as The Vault, is excavated 600ft into the north side of Little Cottonwood Canyon. The vault is owned by The Church of Jesus Christ of Latter-day Saints. The vaults library contains about 35 billion images of genealogical information, mostly on 2.4 million rolls of microfilm and 1 million microfiches. Which equals 3 billion pages of family history records. The vault's library of microfilm increases by up to 40,000 rolls per year. This secret vault is not only unusual and heavily guarded, but it appears to be protected by an intricate temperature control system, including heat and motion sensors as well.

3. Tumen River

Tumen river or Duman river is a 324 mile (521 km) long river border serving China, North Korea, and Russia. The name of the river comes from the Mongolian word tümen, Which means "ten thousand". Tumen River is not only a forbidden place, but it's packed in secrecy. In 1938, the Japanese built the Tumen River bridge, where the Quan river meets the Tumen River.

4. North Sentinel Island

North Sentinel Island is an archipelago in the Bay of Bengal. This island lies 36 km west of the town of Wandoor in South Andaman Island, 5 km west of Port Blair, and 59.6 km north of South Sentinel Island. These Sentinelese are considered as an aggressive and violent tribe. They are in voluntary isolation, totally segregated from the rest of the world. Death cases were reported on several occasions while trying to communicate with The Sentinelese. The Andaman and Nicobar Islands Protection of Aboriginal Tribes Act of 1956 prohibits travel to the island and any approach closer than five nautical miles (9.26 km) to prevent the resident tribespeople from contracting diseases to which they have no immunity. The area is patrolled by the Indian Navy.

5. Area 51

This is the one place that's everybody heard of at least once! Area 51 is the common name of a highly classified the United States Air Force (USAF) facility located within the Nevada Test and Traning Range. For decades, Nevada's Area 51 Air Force facility has been the eye of a conspiracy, they have the evidence that proves extraterrestrials, or so-called "aliens" exists. Apart from these, some even believe that the U.S. government filmed the 1969 moon landing in one of the base's hangar. Many claimed to have the proof of UFO sightings, which of course USAF says to be an experimental airplane test. The perimeter of the base is marked out by orange posts and patrolled by guards in white pickup trucks and camouflage fatigues. The guards are popularly referred to as "cammo dudes" by enthusiasts Signage around the base perimeter advises that deadly force is authorized against trespassers.