Zamek Ogrodzieniec

You're standing at Ogrodzieniec Castle, or rather at what's left of it. These ruins sit on top of Castle Mountain, 515.5 metres high and the tallest hill of the Kraków-Częstochowa Upland. Take a look at the big rocks around the walls. The builders used them cleverly. The walls simply close the circle the rocks already formed. And the entrance? That was just a narrow gap between two of the rocks.