Since 11th century, Schlossberg of Freiburg has been there. There was a fortified castle on the top of the hill, which is beautifully surrounded by greenery. You can climb up the hill to see the turm (tower). However while you do that, keep your eyes turned down to the city of Freiburg. From the top, around 450m, you can see most of the town and the surrounding forest. Breathtaking, I can tell you!