Sens (French pronunciation: [sɑ̃s] ⓘ) is a commune in the Yonne department in Bourgogne-Franche-Comté in north-central France, 120 km southeast from Paris.

[4] Sens is located at the extreme north-west of the Bourgogne-Franche-Comté, on the border of three regions, namely the Île-de-France, the Grand Est and the Centre-Val de Loire.

Located on the course of the river Yonne in the valley of the same name, the city is bordered by the hills of Paron and Saint-Martin-du-Tertre to the west, extension of the plateau of Gâtinais which also extends to the Loiret.

The Battle of the Allia was fought c. 387 BC[5][6] between the Senones – a Gallic tribe led by Brennus, who had invaded Northern Italy – and the Roman Republic.

[9] The site was referred to by Ammianus Marcellinus as Senones (oppidum Senonas), where the future emperor Julian faced an Alamannic siege for a few months, but it did not become an administrative center until after the reorganization of the Roman Empire in 375, when it was the chief town of Lugdunensis Quarta.

The Archdiocese of Sens ruled over the dioceses of Chartres, Auxerre, Meaux, Paris, Orléans, Nevers and Troyes, summarized by the acronym CAMPONT.