The medieval bridge at Warkworth is believed to be the only surviving fortified bridge in England. The guard chamber was used as the village lock-up in the C18th. The bridge was by-passed for vehicular traffic by the construction of the modern bridge immediately downstream.
The Bridge Head Tower is a Grade II Listed Building (List entry Number: 1154927): Link
The only photo posted to date that shows both spans (each 60') of the old bridge, which formerly had a cross ion the centre. Once there was also a portcullis in the gateway at the south end of the bridge. [Murray's Handbook:1890].