Semur-en-Auxois (French pronunciation: [səmyʁ ɑ̃n‿oswa]) is a commune of the Côte-d'Or department in eastern France. The engineer Edmé Régnier L'Aîné (1751–1825) and the Encyclopédiste Philippe Guéneau de Montbeillard (1720–1785) were born in Semur-en-Auxois, while the military engineer Vauban (1633–1707) was educated at the Carmelite college.
Semur-en-Auxois has a medieval core, built on a pink granite bluff more than half-encircled by the River Armançon. The river formerly provided motive power for tanneries and mills, but its flow is now somewhat reduced by the Lac de Pont. The dam was built upstream in the 19th century to provide water for the Canal de Bourgogne.