The gatehouse, called Monnow Gate, which gives Monnow Bridge its now unique appearance, was added at the end of the 13th or start of the 14th centuries, twenty-five to thirty years after the bridge itself was built.[16] The siting of the gatehouse mid-channel is relatively unusual; the archaeologist David Harrison notes the more common arrangement was for the gate to be situated on the roadway at one end of the bridge.[25] In 1297, Edward I provided a murage grant in favour of Monmouth in response to a request from his nephew, Henry of Lancaster. A murage was a medieval tax, granted specifically to allow for the raising of funds to construct or repair town walls.[lower-alpha 5] The grant allowed the townspeople to build the town walls and gates, including the construction of the gatehouse.[15] By 1315, work was incomplete or required repair, as the original authority was renewed on 1 June of that year. At that time, the bridge would have been much narrower than now, with all traffic passing beneath a single arch.