Thérouanne ([teʁ.wan]; West Flemish: Terenburg; Dutch Terwaan) is a commune in the Pas-de-Calais department in the Hauts-de-France region of France[3] 10 km (6.2 mi) west of Aire-sur-la-Lys and 13 km (8.1 mi) south of Saint-Omer, on the river Lys.

According to the historian Malbracq, it got its name from its founder "Lucius Tauruannus",[5] others say it is derived from "Terra avanae" The land of Oats.

Thanks to that ecclesiastical control of some of the most prosperous cities north of the Alps, like Arras and Ypres, the bishopric was able to build a cathedral which was at the time the largest in France.

The town was captured by the Emperor Maximilian and Henry VIII from the French in 1513 after the battle of the Spurs.

Part of the portal of the cathedral was acquired by Saint-Omer; a colossal statue of Christ is all that is left of it these days.