City in Baden-Württemberg, Germany, on the River Neckar, 19 km/12 mi southeast of Mannheim; population (2007 est) 144,600. Industries include publishing, brewing and the manufacture of tobacco products and optics. It is a major tourist centre. Heidelberg University, the oldest in Germany, was established in 1386. The city is overlooked by the ruins of its 13th–17th-century castle, standing 100 m/330 ft above the river.
Heidelberg lies on the south bank of the Necke where it emerges from the Odenwald into the Rhine plain. It once belonged to the bishop of Worms, and later became the seat of the counts and electors of the Palatinate.
Features Buildings include the 15th-century Protestant St Peter's, the university church where Jerome of Prague pinned up his theses in 1460; the fine 15th-century Gothic Heilige Geist Kirche; and the observatory on the Konigsstuhl (1894). The baroque-style Palais Morass contains the Kurpfälzischer Museum (Palatinate Museum), with a varied collection of both historic and artistic interest. In July/August there is a music festival held in Heidelberg Castle, and in April an International Festival of New Music.
Heidelberg Castle The centrepiece of the old city is the castle, guarded by the forest- and vine-clad slopes of Heiligenberg and Konigsstuhl. Begun in the 13th century, the fortress was still being enlarged in the 17th century, but was partially blown up by the French in 1689. In 1764 it was struck by lightning and reduced to its present state of graceful ruin. The castle's cellar contains the Heidelberg Tun, an enormous wine cask with a capacity of 185,500 litres.
Heidelberg University Reformation Calvinist doctrines were disseminated far and wide from the university. It has a valuable library containing about 4,000 manuscripts, 3,000 papyri, and over 500,000 volumes. The collection was begun by Otto Heinrich, and has been housed in the Vatican and at Paris at various times.