The Skull and Bones is a secret society of Yale University undergraduates, with famous alumnus including politicians, lawmakers, members of the Rockefeller family, and three former US presidents including George W Bush. The organisation's headquarters, known as the Tomb, are thought to contain some astonishing and shocking artefacts such as stolen coffins where sex acts take place, a set of Hitler's silverware, and the skulls of several famous historical figures. Frat parties at the Tomb sound pretty bad-ass.
Hangar 18 at the Wright Patterson Air Force Base in Dayton, Ohio is a major source of conspiracy theories regarding alien spacecraft, but the only thing we know for certain about this mysterious building is that inside some form of aviation technology research is taking place, and it's something the military does not want the world to know about.
Because some of the entries on this list are a little heavy we're gonna lighten things up just briefly with a look at Lego's design headquarters in Billund, Denmark.
Whereas the main Lego HQ is located in a huge building with a giant Lego brick planted out front, their secretive design headquarters is actually based in a nearby two-storey office block with no apparent signage or branding. Inside this building a small room of operations is located where only a chosen few of Lego's 3000 local employees have ever set foot.
Pyongyang North Korea, 1987. Construction begins on the Ryugyong Hotel, a project intended to show the world just how powerful and glorious the North Korean regime is. Cut to 2016, and the hotel is still not finished nearly 30 years later, making it the Half Life three of construction projects.
Bureau 39 is another North Korean secret location, but this time we have no confirmed pictures of the building, because this is the site of some extremely shady goings on. Bureau 39 is reportedly where Kim Jong Un's Korean Workers Party orchestrates and executes various illegal activities which take place across the globe, and the CIA estimate that the operations conducted within this one building are responsible for counterfeit US currency production, illegal weapons sales, narcotic production and distribution, and an international insurance fraud scheme, all of which rake in between five hundred million and one billion dollars per year.
It's three in a row for North Korea as in 2015 this ominously designed building was opened - the North Korean Science and Technology Complex known as Ssuk Islet. See how it's shaped like a giant atom? Like something a super-villain would do to his super-secret volcano base? That can't be good, that can't be good at all.
Construction began in 2014 but Kim Jong Un wanted it built quicker than that.
Built in 1994 Vauxhall Cross is one of London's most iconic buildings, and as well as being the place James Bond gets a paycheck it is also the real-life home of Britain's SIS and MI6 intelligence services.