The motte at Monelly is a substantial artificial mound, rising approximately 5.5 to 6 metres high with a flattened summit measuring about 27 metres across. The base of this near oval-shaped structure extends to roughly 39 metres in diameter, and it features a distinctive berm; a level platform or ledge partway up its slope that would have provided additional defensive capability.

Surrounding the motte are the remains of its defensive features, including a fosse or ditch that’s still visible along the eastern and southern sides. This ditch measures about 5.4 metres wide and would have been approximately 0.75 metres deep, though centuries of silting and erosion have likely reduced its original dimensions. An external bank can be seen to the south, which would have been formed from the earth excavated when creating the fosse, adding another layer to the site’s defences.

What makes this site particularly intriguing is the possible remains of a bailey to the north-northwest of the motte. If confirmed, this would classify the site as a motte and bailey castle, the type of fortification favoured by the Normans as they established control over newly conquered territories in the 12th and 13th centuries. These structures served as both military strongholds and administrative centres, with the motte topped by a wooden tower or keep, whilst the bailey would have contained buildings for garrison, storage, and daily life. The site was first documented by historian William Carrigan in 1905, and later included in the Archaeological Inventory of County Laois published in 1995.