Built from coursed granite blocks, this L-shaped fortification stretches approximately 26 metres from southeast to northwest, with another section running about 17.5 metres from southwest to northeast. The wall connects what was once a formidable defensive complex, linking a tower house to a gatehouse, creating a protected courtyard space typical of medieval Irish strongholds.

The site's history stretches back to its days as a Cistercian grange belonging to St Mary's Abbey. Following the dissolution of the monasteries in the sixteenth century, these lands passed through several notable hands. Sir John Travers, Master of the Ordnance of Ireland, received the property first, followed by Walter Cheevers who held it in 1641. During the Cromwellian period, ownership transferred to Ludlow Cromwell, Master of the House, who reportedly restored the castle and created formal gardens on the grounds.

A fascinating glimpse of the site's former glory comes from a 1766 drawing by artist Beranger, which depicts a much grander complex than what remains today. His illustration shows two towers positioned at either end of a courtyard, with a multi-chimneyed mansion along one side and an ornamental show wall on the other; a testament to how this medieval fortification evolved into a comfortable residence over the centuries. Today, while much reduced from its former extent, the surviving bawn wall serves as a tangible link to Monkstown's rich medieval and early modern past.