HEIDELBERG, a town of Germany, on the south bank of the Neckar, 12 m. above its confluence with the Rhine, 13 m. S.E. from Mannheim and S4 m. from Frankfort-on-Main by rail. The town lies between lofty hills covered with vineyards and forests, at the spot where the rapid Neckar leaves the gorge and enters the plain of the Rhine. The town itself consists practically of one long, narrow street—the Hauptstrasse—running parallel to the river. A number of smaller streets intersect the Hauptstrasse at right angles and run down to the river. Heidelberg is an important railway centre, and is connected by trunk lines with Frankfort, Mannheim, Karlsruhe, Spires and Wurzburg. Of the churches the chief are the Protestant Peterskirche dating from the 15th cen tury and restored in 1873, to the door of which Jerome of Prague in 1460 nailed his theses; the Heilige Geist Kirche (Church of the Holy Ghost), an imposing Gothic edifice of the 15th century; and the Jesuitenkirche (Roman Catholic), with a decorated interior.
Heidelberg castle, overhanging the east of the town, stands on the Jettenbiihl, a spur of the Konigsstuhl (1,80o ft.), 33o ft. above the Neckar. It is one of the chief monuments of Germany, begun in the 13th century and extended by addition of a wing, Ruprechtsbau, under the elector palatine and the German king Rupert III. (d. 1410). Otto Henry "the Magnanimous" (d. ), built the beautiful early Renaissance wing (1556-59) ; the fine late Renaissance wing called the Friedrichsbau was added (1601-07) under Frederick IV. ; and, on the west side, the Elisabethenbau or Englischebau (i618), named after his wife, the daughter of James I. of Great Britain, built under Frederick V. At the peace of Westphalia, Heidelberg was given back to Frederick V.'s son, Charles Louis, who restored the castle. At the end of the 17th cen tury it was despoiled by the French and finally, in 1764, it was struck by lightning and reduced to ruin. Apart from outworks, the castle is an irregular square with round towers at the angles, the principal buildings being grouped round a central courtyard containing the Alte Bau and the Bandhaus with the entrance from the south through a series of gateways. In this courtyard, besides the buildings already mentioned, are the oldest parts of the castle, the so-called Alte Bau (old building) and the Bandhaus. The Friedrichsbau was elaborately restored and rendered habitable be tween 1897 and 1903. The fountain in the courtyard is decorated with four granite columns from Charlemagne's palace at Ingel heim; the Elisabethentor is a beautiful gateway named after the English princess, there is a beautiful octagonal bell-tower at the north-east angle; and the castle chapel and the museum of an tiquities are in the Friedrichsbau. In a cellar entered from the courtyard is the famous vat built in 1751, which has been used only occasionally. Its capacity is 49,00o gal., and it is 20 ft.
high and 31 ft. long. Behind the Friedrichsbau is the Altan (161o), or castle balcony with a magnificent view.
The university of Heidelberg was founded by the elector Rupert I., the bull of foundation being issued by Pope Urban VI. in 1385. It was constructed after the type of Paris, and had four faculties; Otto Henry gave it a new organization, further endowed it and founded the library, first kept in the choir of the Heilige Geist Kirche, and consisting of 350o mss. In 1623 it was sent to Rome by Maximilian I. of Bavaria, and stored as the Bibliotheca Pala tina in the Vatican. It was afterwards taken to Paris, and in 1815 was restored to Heidelberg. At the Reformation it became a strong hold of Protestant learning. Damaged by the Thirty Years' War, it led a struggling existence for a century and a half and many of its endowments were cut off by the peace of Luneville (i8oi). In 1803, however, Charles Frederick, grand-duke of Baden, raised it anew and reconstituted it.
Heidelberg makes metalware, pianos, cigars, leather, cement, surgical instruments and beer, but is largely concerned with cater ing for tourists and students. Pop.