Ehrenbreitstein (i. e., the broad stone of honor), a town of Prussia, on the right bank of the Rhine, opposite Coblentz, with which it is connected by bridges; pop. in 1871, 2,504, exclusive of the garrison. It is situated at the foot of a rocky height, upon which is the fortress. The fortress of Ehrenbreitstein was probably founded by the Romans under the emperor Julian, was rebuilt in the 12th century by Hermann, archbishop of Treves, and became of great strategical importance during the thirty years' war. The French under Marshal Boufflers, aided by Vauban, in vain besieged it in 1688. They assailed it again at the end of the following century, but gained possession of it (January, 1799) only after a siege of 14 months, and after reducing the garrison to starvation. In 1801 they blew up its defences, but the fortress was subsequently rebuilt by Prussia. The works will lodge 100,000 men, yet a garrison of 5,000 is deemed sufficient to defend them. The magazines are •capable of containing provisions for 8,000 men for ten years. The escarped rocks and steep slopes on three sides of the fortress seem impregnable.
The platform on the top of the rock serves as a parade ground, and covers vast arched cisterns capable of holding a three years' supply of water, which is obtained from springs without the walls.