The site at Lismalin consists of a tower house surrounded by a bawn, a defensive courtyard wall typical of Irish fortifications from this period. The Civil Survey of 1654-6 described it as a ‘good castle with bawne & twelve cabbins’, noting that it had been recently repaired at state expense. Pierce Butler, Lord Viscount of Ikerryn, held the property in 1640, and the survey confirms the castle was inhabited and its bawn strengthened during this time of political upheaval.

The bawn walls, originally measuring approximately 46 metres north to south and 40 metres east to west, can still be traced along the northern and eastern sides of the tower house. The eastern wall stands particularly well preserved at about three metres high, constructed from limestone rubble without the base batter typical of many defensive walls. A two-storey farmhouse from the 17th or 18th century was cleverly incorporated into the northeast corner of the bawn, using the original defensive wall as part of its structure. This northern wall extends intact for 21.5 metres before meeting what is now a modern driveway, likely the location of the original entrance to the fortified compound.

Archaeological evidence suggests the site may have had two phases of construction; a protruding wall at the southeast corner could be the remains of an earlier, smaller bawn, whilst the larger enclosure visible today might represent the 17th-century expansion mentioned in historical records. Today, the interior of the bawn contains various farm buildings and two dwellings, including a 20th-century cottage near the northwest corner. Though the southern and western walls have disappeared, the site’s elevated position still offers commanding views across the landscape from west through north to east, reminding visitors why this spot was chosen for defence centuries ago.