The ruin of a late 18th century castellated house known as 'Byrne's Folly' stands on top of the mound of Castletown Motte. It was built by Patrick Byrne, a well-known pirate, in 1780 ad. The motte is built on the site of a pre-Christian fort called Dún Dealgan, meaning 'The Fort of Dealga'. This site is important in Irish mythology as it is said to be the birthplace of the legendary warrior - Cúchulainn.
The standing stone that supposedly marks his burial can be seen in the field to the right as you go up the entrance lane. Access : Requires climbing over an old stone stile in the stone wall at the entrance.
The site is located on 'Mount Avenue' on the western edge of Dundalk Town. Mount Avenue lies on the south side of the N53 Dundalk to Castleblayney round, 2km from Dundalk town centre.