As soon as we've decided we know everything about famous sights of the world - if not in person, then thanks to the Internet - we learn there are more secrets to find that aren't known to the general public. Did you know, for example, that when Gustave Eiffel was designing his famous tower in Paris, he added a secret apartment for himself right on top of it? Visitors to the third level can now take a glimpse of the apartment through a small window.

Or have you ever heard of secret apartments in the New York public libraries? They’re meant for the library superintendents and their families. They used to live, cook meals, take showers, and do other regular things in the Schwarzman Building on 5th Avenue. They also had a cool bonus of walking the library rooms at night. So let's take a tour around some of the world's greatest sights and take a look at what else they have to offer that doesn't meet the eye at once.

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