Bonnybridge Motte

Bonnybridge Motte is a badly damaged ditched motte situated on the north side of the earthworks of the Antonine Wall, utilising the ditch as part of its defences. The enclosed mound measured perhaps 25 metres east-west by 13 metres north-south, and stood about 3.5 metres above the ambient ground level. Today it is overgrown by trees and sits within the grounds of a primary school. The medieval ditch has largely filled in, and the Roman section has been levelled.

A pottery fragment dating to c1200 was found on the site, which is consistent with a general dating of the motte, which overlooked a ford of the River Bonny to the north, and later served as the seat of the barony of Seabegs. There are several mottes of this type on the Antonine Wall, the best preserved of which is in the park at Kirkintilloch. By the 15th century, Seabegs was held by the Straton family of Laurieston, and served as a “court hill” by the 1540s. Excavations recorded in v34 of the Proceedings of the Society of Antiquaries of Scotland did not find evidence of buildings, which were presumably of timber. I have not been able to find earlier documentary references to Seabegs to further illustrate the history of the mound at the time of writing (February 2025)

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