Heidelberg's main tourist destination is the Heidelberg castle, as much of the city's history remains there. The castle experienced many destructions including the 30 Years' War and the removal of stones from the castle for houses in the city. By 1800 the abuse was ceased, and the castle was used and preserved.
Not only does the Heidelberg Castle offer history of the town it also gives a bird's eye view of it, which can be achieved nowhere else.
The walk up to the castle is about 15 minutes, and visitors can tour the castle for as long or short of a time as they want.