Heidelberg, an ancient city of Baden, extends 3 miles along the left bank of the Neckar, in one of the most beautiful districts in the country, 13 miles by rail SE. of Mannheim and 54 S. of Frank-fort-on-the-Main. It lies 380 feet above sea-level, at the base of the Konigsstuhl (1863 feet). Among its most important buildings are the Church of the Holy Ghost, a splendid example of Late Gothic architecture, in which service according to the Catholic and Protestant rituals is simultaneously carried on ; the church of St Peter's, on the door of which Jerome of Prague nailed his celebrated theses; and the magnificent castle, which crowns a hill 330 feet above the town. Begun at the close of the 13th century, and added to in 1410, 1559, and 1607, it was formerly the residence of the Electors Palatine, and was in great part destroyed by the French in 1689 and 1693, and further injured by lightning in 1764. In 1890 was undertaken the work of restoring its ruins at a cost of £50,000. In the cellar under the castle is the famous Heidelberg Tun, once capable of containing 50,000 gallons of wine. Heidelberg is celebrated for its university (1386), which declined from the Thirty Years' War until 1802, when the town and territory was assigned to the Grand-duke of Baden. It has about 150 professors and lecturers, and over 1500 students. Its library contains 500,000 volumes and 4700 MSS. Many of the most famous German scholars have been professors here - Reuchlin, Œcolampadius, Spanheim, Puffen-dorf, Voss, Schlosser, Creuzer, Gervinus, Paulus, Kuno Fischer, Helmholtz, Bunsen, Bluntschli, etc. Heidelberg, originally an appanage of the bishopric of Worms, was the seat of the Counts Palatine from the 12th till the 18th century. After the Reformation it was long the headquarters of German Calvinism. The trade is chiefly in books, tobacco, beer, and wine. The town suffered much during the Thirty Years' War, was savagely treated by the French in 1689, and was in 1693 almost totally destroyed by them. Pop. (1871) 19,988; (1900) 40,121, of whom two-fifths are Catholics.