English: Rough outline of the Roman Catholic diocese of Constance (Konstanz), whose boundaries didn't change from the 8th century to 1814, when the various parts of the diocese in Switzerland were apportioned to various Swiss dioceses. A large number of parishes had been lost to Protestantism during the Reformation.

The small territories in red constituted the Prince-Bishopric of Constance, over which the Prince-Bishop ruled as a secular sovereign. In 1526, the Prince-Bishop moved out of the Free Imperial city of Konstanz and settled in Meersburg, on the northern shores of Lake Constance.

While the fragmented Prince-Bishopric of Constance was one of the smallest and most insignificant of the Holy Roman Empire (a little less than 500 sq. miles), the diocese of Constance, over which the Prince-Bishop exercised only the spiritual authority of an ordinary bishop, was the largest of Europe by the late 18th century.