Lons-le-Saunier (French pronunciation: [lɔ̃s lə sonje] ⓘ) is a commune and capital of the Jura Department, eastern France.

The Jura escarpment extends to the east and south, while to the west lies the plain of Bresse and to the north extensive vineyards.

The river Vallière runs through the town, rising in a typical Jura blind valley not far away, at Revigny.

The town is approximately equally placed between Besançon, Dijon, Bourg-en-Bresse and Geneva, though the last of these lies on the other side of the Jura massif.

[5] In the 19th century there were copper and iron foundries, and a trade in horses, cattle, grain, cheese, etc.