From Fort Knox to the LDS Church's vaults in Little Cottonwood Canyon to the underground nuclear shelter at The Greenbrier, take a look at eight sites throughout the world that are or were heavily guarded.
Information was compiled by Can You Actually, and supplemented by our own research.
This list is not exhaustive and locations are listed in no particular order.
Fort Knox is used as an Army training center, according to the Fort's official website.
In the past it stored the Magna Carta, the U.S. Constitution and Lincoln's Gettysburg address, according to the United States Mint.
It also houses 147.3 million ounces of gold in the United States Bullion Depository, the United States Mint reports.
Inside the depository, there is a steel and concrete vault that spans two levels and is split into various compartments, according to the U.S. Treasury.
The door of the vault weighs upwards of 20 tons. The vault's total combination is not known to a single person; different depository staff members dial a specific portion of the combination.
The depository "is equipped with the latest and most modern protective devices," The Treasury reports.
This military installation site has long been shrouded in secrecy (the CIA finally admitted its existence in 2013, CNN reports.)
This secrecy has perhaps led to the site's notorious reputation as a government testing and storage site for all things extraterrestrial.
Top security clearance and an invite from military or intelligence officials are required to get access to the area.
Pairs of men dressed in camouflage patrol the perimeter of Area 51, according to How Stuff Works.
Security sensors are embedded around the base's perimeter and public use is restricted in most areas surrounding the base.
For more information, visit How Stuff Works.
Here's yet another secure facility carved out of a granite mountain.
The Cheyenne Mountain facililty was built to hold up against a nuclear strike, or chemical and biological attacks, according to a a 2007 letter written to Congress by the U.S. Government Accountability Office.
It used to operate as a command center for many of NORAD's operations. Now it is an alternate command center to warn officials about aerospace and ballistic attacks against North America.
We could not find much information regarding the security of the Cheyenne Mountain location. What we do know is it is a NORAD facility and tours to the public are restricted.
For more information visit the NORAD Cheyenne Mountain website or Facebook Page.
The unoccupied space between North and South Korea is 148 miles long 2.5 miles wide, according to the National Geographic. It is heavily guarded by troops on both sides.
Anyone who tries to cross the Military Demarcation Line would probably be shot, the National Geographic reports.
It has been guarded since July 1953 when the Korean peninsula was divided at the 38th parallel.
For more information visit National Geographic.
Those who run this car park tout it as the world's safest.
Upon entering the park, each person receives a Smartcard that records information about the vehicle and driver, according to Parksafe. Before leaving the park, the driver needs to scan the Smartcard.
Once past an initial barrier arm, there are double gates at the entrance of the parking garage.
Each parking spot has a motion sensor installed, Parksafe reports. Cameras located throughout the park turn on if sensors are activated.
Every pole in the garage has a panic button that activates a camera to transmit information back to the control room.
As of 2011, the car park had not seen any crime, according to Parksafe.
Tunnels carved into the granite of Little Cottonwood Canyon house billions of images containing genealogical information.
The facility is also a deep-storage center for LDS Church operational, leadership and history materials.
The vault is not open to the public for security purposes, although at one time it was.
Archivists cite concerns about protecting the materials inside the vault from visitor fingers and contamination from small particles, such as the dust that brushes off jeans when one walks.
For more information, check out an earlier article by the Deseret News.
In addition to other treasures, the Federal Reserve Bank stores gold belonging to the U.S and foreign governments, other banks and international organizations in its basement, according to the Federal Reserve Bank's website.
About 530,000 gold bars, weighing roughly 6,700 tons, were in the vault as of 2012.
Every compartment in the vault is secured by a padlock, two combination locks and a seal by the auditor.
Two New York Fed gold vault staff members and one internal audit staff member need to be in attendance when gold is moved or a vault compartment is opened.
A 90-ton, 9-foot-tall cylinder made from steel is at the vault's only entrance. It sits inside a frame made from steel and concrete that can create a seal that is air- and watertight.
Once this is closed, four rods made of steel are placed inside holes in the cylinder and timers are set, keeping the vault locked until the next business day.
This is just the beginning of the vault's security measures. For more information, visit the Federal Reserve Bank of New York's website.
Although no longer secure, this location deserves a place on our list for being so secure it eluded detection for decades.
For decades the Greenbrier Resort in West Virginia contained a nuclear bunker filled with supplies, ready to house members of Congress, NPR reports.
The bunker was a secret for 30 years before it was discovered in 1992.
It was built in the late '50s under President Dwight Eisenhower as a way to keep the country running in the event of a nuclear war, according to NPR.
People regularly used the bunker for mundane conferences without knowing they were in a bunker.
A space that NPR describes as "about the size of a WalMart" is housed behind 3-foot wide concrete walls.
It is now open to the public for tours.
A new bunker is housed in a new location, unknown to most, NPR reports.