Teufelsberg (Devil's mountain), located in west Berlin, Germany, has a most unique history. With its 375 ft (114 m) it is the highest hill in the Berlin area, and it's man-made! It is made of 12 million cubic meter rubble, from about 400,000 destroyed buildings, during the rebuilt of Berlin after the Second World War.
All the walls are covered in graffiti and the view is amazing! Worth paying 7 euros which are charged at the entrance.