Langres Cathedral is a Roman Catholic church in Langres, France. It was erected in the twelfth century, and is dedicated to the 3rd-century martyr Mammes of Caesarea. The cathedral is the seat of the Bishop of Langres, and is a national monument. The nave and interior are in the Romanesque and French Gothic style while the later facade is an example of French Neoclassical architecture

Langres is a commune in northeastern France. It is a subprefecture of the department of Haute-Marne, in the region of Grand Est.