The stone bridge was completed in the late 13th century. It was traditionally thought to have been built in 1272, though this date has no supporting documentary evidence.[15][lower-alpha 2] The historian William Coxe incorrectly described the bridge as pre-dating the Norman Conquest and recorded that "it commanded the passage of the Monnow and was a barrier against the Welsh".[17] In 1804, the Monmouth antiquarian Charles Heath wrote that the bridge's "foundation is so ancient that neither history or tradition afford any light respecting the date of its erection".[18] Heath drew directly from The Antiquities of England and Wales, an earlier guide by Francis Grose, published in 1773.[19] The archaeologist Martin Cook notes the significance of the date 1270 as the start of a period that saw increased bridge-building, as a result of the rapid growth of international trade.[20][lower-alpha 3] The civil engineer Edwyn Jervoise suggested that the absence of an evidential record was due to the destruction of the archives of the Duke of Beaufort at Raglan Castle in the 17th century.[22] This is unlikely, as the gatehouse did not come into the possession of the duke's family, the Somersets, until the 19th century.[23][lower-alpha 4]