Dubrovnik, Croatia: Fort Bokar

Imagine coming up to this as an invader of Dubrovnik in the Middle Ages. It would be tempting to say, "Nope, no chance here," and order everyone to turn around. 

That's what Fort Bokar must have done to people in that era. It was built starting in 1461, and designed to protect one of the gates to the city. Ninety years later, the Fort was open for business. Believe it or not, there was some debate at the time as to whether construction should be finished. Since it is on a detached rock, you can watch the sea water passing right by it. 

Now tourists who walk the walls of the city stop by to see the collection of cannons. The place is used for the Dubrovnik Summer Festival.  

And if you watched the television series "Game of Thrones," you might recognize the area. There's a small beach nearby that's worth a look too.