North Yorkshire County Council's bridges team will be repointing part of the northwest turret of Middleham Bridge, a castellated structure designed to echo Middleham Castle and the area’s links with Richard III.
Excess movement at the join between the parapet and the turret has caused the mortar to crack.
Councillor Karin Sedgwick, member for the Middle Dales division, said: “In recent years Middleham Bridge has been used and admired by people around the world during the Tour de France and UCI World Championships, and is very popular with tourists. It is vital we keep this historic structure in the best possible condition.
“We appreciate that the closure and lengthy diversion will be an inconvenience for many but ask the public for their patience while the maintenance is being carried out.”
Work will begin on July 5 and will last for three days. During the working hours of 8am to 6pm the bridge will be closed to road users and pedestrians. Emergency vehicles will have access.
In 1829, a simple suspension bridge was built over the River Ure to replace the ford at Western Willows, but after only a year it collapsed under the weight of a herd of bullocks being driven across the bridge and “getting into step”.
It was repaired and made a deck bridge. Soon after a toll was introduced to pay for its upkeep. In 1864 the bridge was replaced by an iron girder one and the toll continued until 1880, when it was taken over by the county’s highways.