Chatelet (Lat. Castcllucium), the name of two fortresses which existed in Paris in former times, said to have been built by Julius Ca3-sar. The Grand Chatelet was restored and enlarged by Louis IX., Charles VIII., and Louis XII., remodelled by Louis XIV., and demolished in 1802. It stood on the right bank of the Seine, in the locality now occupied by the western part of the place du Chatelet. It was the residence of the counts and afterward of the provosts of Paris, and became celebrated as a prison and as an important seat of the judiciary. At the time of the suppression of the latter in 1790, the court contained, from the provost down to the ushers and policemen, 1,207 officers, besides a large number of lawyers who transacted business there, and the military forces of the Chatelet, which consisted of two companies of soldiers, part of whom were at the same time employed as ushers. The Petit Chatelet was situated on the left bank of the Seine, on the site of the present place du Petit Pont; swept away by an inundation in 1296, it was rebuilt in 1369, and demolished in 1782. Originally it was one of the gates of Paris, where tolls and excise duties were levied.

The chatelets at Orleans and Montpellier were, like those of Paris, the seats of judicial bodies.