Konigstein is a town of Germany, in the kingdom of Saxony, situated in a deep valley on the left bank of the Elbe, at the influx of the Biela, in the centre of Saxon Switzerland, 2.5 m. S.E. of Dresden by the railway to Bodenbach and Testchen. It contains a Roman Catholic and a Protestant church, a monument to the composer Julius Otto, and has some small manufactures of machinery, celluloid, paper, vinegar and buttons. It is chiefly remarkable for the huge fortress, lying immediately to the north-west of the town, which crowns a sandstone rock rising abruptly from the Elbe to a height of 750 ft. Across the Elbe lies the Lilienstein, a similar formation, but unfortified. The fortress of Kdnigstein was probably a Slav stronghold as early as the 12th century, but it is not mentioned in chronicles before the year 1241, when it was a fief of Bohemia. In 1401 it passed to the margraves of Meissen and by the treaty of Eger in 1459 it was formally ceded by Bohemia to Saxony. About 1540 the works were strengthened, and the place was used as a point dappui against inroads from Bohemia. Hence the phrase frequently employed by historians that KOnigstein is the key to Bohemia. As a fact, the main road from Dresden into that country lies across the hills several miles to the southwest, and the fortress has exercised little, if any, influence in strategic operations, either during the middle ages or in modern times. It was further strengthened under the electors Christian I., John George I. and Frederick Augustus II. of Saxony, the last of whom completed it in its present form. During the Prussian invasion of Saxony in 1756 it served as a place of refuge for the King of Poland, Augustus III., as it did also in 5849, during the Dresden insurrection of May in that year, to the King of Saxony, Frederick Augustus II. and his ministers. It was occupied by the Prussians in 1867, who retained possession of it until the peace of 1871. It is garrisoned by detachments of several Saxon infantry regiments, and serves as a treasure house for the state and also as a place of detention for officers sentenced to fortress imprisonment. A remarkable feature of the place is a well, hewn out of the solid rock to a depth of 470 ft.