Scrolling the vastness of the internet you may stumble upon, like we did, a list of the most heavily guarded places on earth. Intrigued, you may click and find that Iron Mountain is one of those listed places.

You may be expecting locations like the US Military's Cheyenne Mountain Complex or the Vatican archives - both on the list - but what about Iron Mountain? A true Michigander would immediately think of the city in the Upper Peninsula on the border with Wisconsin and wonder what is so top secret about Iron Mountain and who are they trying to keep out, Wisconsinites or maybe the riffraff from neighboring Kingsford?

In fact, no, none of that is true. Iron Mountain in Michigan is open and welcoming. But the Iron Mountain in Pennsylvania is a whole different story. This Iron Mountain is not a city but rather a huge underground storage facility.

Built into a former limestone mine in Western Pennsylvania, Iron Mountain is touted as holding a

treasure trove of information from government records to corporate documents to master recordings of legendary artists.

In a profile piece on, the complex is considered a secret even to those living nearby and virtually unknown to anyone not from nearby. What's it like inside? Iron Mountain

house[s] data centers, including many of those belonging to government agencies and private companies.

The mine is like a small underground city. It has its own fire brigade with trained firefighters, security, streets, a speed limit (10 mph), traffic signs, street names, pedestrian walkways and addresses assigned to its thousands of tenants that occupy its 16-foot-high corridors.

So should you ever hear about a secretive Iron Mountain know it's an underground facility beneath the western Pennsylvania mountains and not a quiet, but very open, city in the central Upper Peninsula.

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