The principal monument in the town is the Ardee Castle, now the Court House (Main Street). The 13th century square keep is reputed to have been built by Roger Pipard. In its day it was an important border-fortress of the English Pale. After the Restoration it was granted to Theobald Taafe, Earl of Carlingford (1639-77).

The castle functioned as a prision in the later centuries and a bridewell was built after a design by Nerville during the nineteenth century. Permission to view may be had from the Town Clerk.