Carrickmacross (Irish: Carraig Mhachaire Rois, meaning "rock of the wooded plain") is a town in County Monaghan, Ireland. The town and environs had a population of 4,925 according to the 2011 census, making it the second largest town in the county. The town won the prestigious European Entente Florale Silver Medal Award. It is a market town which developed around a Castle built by the Earl of Essex in 1630. The Convent of the St. Louis Nuns now stands on the original castle site.