Heidelberg Castle — the Heidelberger Schloss — is one of the most visited ruins in Germany and the defining image of the city. It sits on the Königstuhl hillside some 80 metres above the Altstadt, accessible by the Bergbahn funicular from the Kornmarkt or by a steep footpath. The castle was built up over several centuries by the Electors Palatine and at its height was one of the great Renaissance palaces north of the Alps. The French destroyed much of it in 1693 during the Nine Years' War and lightning strikes in the 18th century finished the work, leaving the photogenic mix of intact buildings and dramatic red-sandstone ruin that visitors see today.
The highlight of the interior courtyard is the Ottheinrichsbau, a Renaissance façade from the 1550s considered one of the finest examples of Renaissance architecture in Germany. Inside the cellar is the Großes Fass — the Great Barrel — a wine cask built in 1751 with a capacity of 220,000 litres (the largest wine barrel ever built), next to which stands a statue of Perkeo, the legendary dwarf court jester said to have drunk it dry. The Deutsche Apothekenmuseum (German Pharmacy Museum) occupies part of the castle and is surprisingly engaging, tracing the history of European pharmacy from the medieval period onwards.
The castle gardens (Hortus Palatinus) on the terraces below were designed in the early 17th century by Salomon de Caus and offer sweeping views over the Altstadt and the Rhine plain. Three times a year — typically the first Saturday of June, the last Saturday of July, and the second Saturday of September — the castle is illuminated with fireworks over the river in the Schlossbeleuchtung, a tradition recreating the French bombardment of 1693 that has been running since 1830.