HORN-CASTLE, a town of England, in Lincolnshire. It had a castle, as the name imports; from the architecture of which, and the Roman coins that are sometimes dug up here, it is thought to have been a camp or station of the Romans. The town is well built, and is almost surrounded with water. It is a signiory of 13 lordships, in which are several chapels. Horn-castle contained in 1801 above 2000 inhabitants, who are principally occupied in the manufacture of leather. It has a market on Saturdays, and fairs in June and August.