Mystery of Castell Glas & Ebboth Castle

Description

Within the modern landscape of Maesglas, Newport, Castell Glas (meaning "Green Castle" in Welsh) is a little-known medieval motte-and-bailey site with a rich but largely forgotten history. This site, also referred to as Greenfield Castle or Maesglas Castle, played a role in Newport’s feudal past and may even be linked to the mysterious lost stronghold of Ebboth Castle.
In the case of Castell Glas, the name might have referred to the surrounding landscape rather than the colour of the castle itself. Given that "Greenfield" is another historical name for the site, it's possible that in this context, "Glas" meant "green" rather than "blue."
Dating back to the Norman period, Castell Glas was constructed as a motte-and-bailey fortification—a defensive structure consisting of a raised earthwork (motte) supporting a wooden or stone keep, surrounded by a lower courtyard (bailey). Such castles were common across Wales following the Norman invasion as a means of asserting control over the land.
Today, the physical remnants of Castell Glas are subtle but still visible. A rectangular mound, measuring approximately 25 meters across, remains within a children’s play area near a modern housing estate in Maesglas. Historical records, including observations by D.J.C. King, describe this as the remains of a motte that was once associated with stone masonry, suggesting later modifications to the original wooden structure.
The site gained attention in 1892, when William Henry Greene sketched a castle doorway, possibly linked to Maesglas Farm, hinting at surviving medieval structures in the area. Older historical descriptions suggest that Castell Glas included a tower with a spiral staircase, a stone-built hall, and Gothic-style doors and fireplaces, elements that were later incorporated into a farmstead. By 1622, the site had been sold, and by 1645, records indicate
that it had disappeared. However, accounts from the 18th century still describe visible remnants of medieval stonework.
Castell Glas was once associated with the Kemeys family, influential landowners in South Wales who also controlled Rogerstone Castle (Tribginlion) and other estates. Over time, the site faded from prominence, eventually being absorbed by later developments in Newport.
For those interested in visiting, Castell Glas is located in the Gaer community of Newport, with the Ordnance Survey Grid Reference ST302858.
In modern Welsh, "glas" typically means blue, but historically, it could also mean green, grey, or even a blue-green shade, depending on context. In medieval Welsh, "glas" was often used to describe natural features like rivers, fields, or foliage, where it could mean "lush green" or "blue-green."
Sources:
• William Henry Greene’s 1892 sketch of the castle doorway (Torfaen Museum Trust).
• Gatehouse Gazetteer, listing Castell Glas as a medieval motte site.
• Castle Wales website, detailing the Kemeys family's landholdings.
• Historical records of Newport and Monmouthshire

• https://tinyurl.com/Mystery-Castell-Glas (link opens in new window)