The capital of the Austrian empire, on a southern branch of the Danube, in a situation calculated to make it the central city of the Continent; it is the residence of the emperor and the seat of the government; has noble buildings, a university, and numerous large libraries, a large promenade called the Prater, and a varied industry, and ample means of both external and internal communication; in the SW. of it is Schonbrunn, the summer residence of the emperor, amid gardens of matchless beauty; it has been the scene of the signing of important treaties, and it was here the Congress met to undo the work of Napoleon in 1815.