Perched enticingly above the Altstadt, set amid woodlands and terraced gardens, Heidelberg’s half-ruined castle has impressed everyone from kings and princes to the poet Goethe, novelists Victor Hugo and Mark Twain, and millions of visitors for whom the red sandstone walls clinging to the green hillside are the epitome of German romanticism. Even in ruin one of the great Renaissance landmarks of northern Europe suggests beauty, grandeur, and long vanquished empires—in this case a division of the Holy Roman Empire known as the County Palantine of the Rhine, whose prince electors lived here from the 13th century.

Elizabeth, the teenaged daughter of English King James I who married prince elector Frederick V and came to Heidelberg in 1605, entered the castle through the portal named for her, Elizabeth’s Gate, as visitors still do. The soulless salons of the heavily restored Friedrichsbau, the early-17th-century palace where the young couple took up residence, are less evocative than the shells of most of the rest of the compound’s royal enclaves, laid waste to in 1690 by the French troops of Louis XV and finished off by a disastrous lightning strike. Enough gables and arches remain to suggest the grandeur of the place, and a multilanguage audioguide does a good job of filling in the missing pieces.

An especially noteworthy relic is the Great Cask, aka the Heidelberg Turn, a symbol of the exuberant life of the prince electors enjoyed. The vulgar vessel was built in 1751 to store more than 208,000 liters (55,000 gal.) of wine but failed to impress Mark Twain, who wrote, “An empty cask the size of a cathedral could excite but little emotion in me.” The Chemist’s Tower houses the Apothekenmuseum (Pharmaceutical Museum) and the old chambers quite engagingly spotlight the importance of German pharmaceutical research (much of it conducted at Heidelburg University) with utensils, laboratory equipment, and a re-created chemist’s shop from the 18th and 19th centuries. The castle’s perennial crowd pleaser are the views that stretch across the old town and down the Neckar Valley. You can enjoy them 24 hours day, since the castle courtyard is always open, as is the shady Schlossgarten.

You can reach the castle by several routes. The Bergbahn (mountain train) whisks you up from the Kornmarkt in a flash (tickets to the castle include the train ride). A paved road gradually winds up the Neue Schlossstrasse past told houses perched on the hillside, while the steeper Burgweg walk climbs uphill from Kornmarkt.