(Costnitz), the capital of the Baden See-Kreis or Lake Circle, situated on the Swiss side of the Rhine, on a peninsula at the W. extremity of the Bodensee or Lake of Constance. It is an ancient town, and its population has fallen from 40,000 in the fifteenth century to 5300 in the present. Its fortifications consist of a wall flanked by towers, and one of its suburbs, that of Kreuzlingen, is defended by two bastions. The suburb of Petershausen, which was originally a free abbey of the empire, communicates with the city by means of a long covered wooden bridge raised on stone piers. The only other suburb, that of Brühl, contains the field in which Huss suffered martyrdom. The principal buildings of Constance are the minster, the old Dominican convent on the island of Geng, now a cotton-printing establishment, and the Kaufhaus or public mart, in the hall of which sat the famous council of Constance (1414–15). It contains also a lyceum, a hospital, a conventual school for females, and several museums. Constance is the seat of the circle and district governments, and has a considerable local trade. There are a few manufactures of cotton and silk stuffs; and a considerable proportion of the inhabitants are engaged in the fisheries and navigation of the lake.

Constance, Lake of (Bodensee Costnitz), a large lake of Central Europe, on the confines of Baden, Württemberg, Bavaria, Austria, and Switzerland. Greatest length from Bregenz to Bodmann 44 miles; greatest breadth between Rorschach and Friederichshafen 18 miles; greatest depth 912 feet; height above the level of the sea 1280 feet. It is divided into the upper and lower lakes, the latter of which contains the fertile island of Reichenau. They are connected with each other by the channel of the Rhine, which enters the lake at Rheineck, and leaves it at Stein. The shores of the lake are flat and undulating, being more fertile than picturesque. The navigation is rendered dangerous by sudden squalls, but there is a considerable traffic in rural produce, and numerous steamboats ply between the towns on the margin of the lake. Its waters are subject to sudden risings, proceeding from some unknown subterraneous agency: they abound in salmon, trout, pike, carp, &c., and are frequented by numerous species of aquatic birds. To the Romans the lake of Constance was known as the Brigantinus Lacus. Its northern shore was inhabited by the Vindelicians, the southern bank was held by the Helvetians, and the south-east by the Retauns.