Bideford Long Bridge in North Devon spans the River Torridge near its estuary and connects the old part of the town, and formerly important river port, of Bideford on the left bank (west side) with East-the-Water on the right bank (east side). It is one of the longest mediaeval bridges in England, being 677 feet (222 yards) long with 24 arches. In 1790 the bridge was the longest in Devon. It remained the furthest downstream bridge on the river until 1987, when the Torridge A39 Road Bridge was built a mile or so further downstream at Northam. The river is still tidal at Bideford (and as far upstream as Weare Giffard) and a very large fluctuation in water levels occurs twice daily under the bridge. An ancient New Year's Eve tradition was to try to run across the Long Bridge during the time taken for the bells of St. Mary's parish church, near the west end, to chime midnight. A sight enjoyed by many in the winter months is of the starlings at dusk, as they come in large flocks to roost underneath the bridge.
It is a Grade I listed building. Another major medieval bridge, the Barnstaple Long Bridge in Barnstaple over the Taw, is a few miles away.
The Devon historian Hoskins (1959) stated that the first bridge was built in the last quarter of the 13th century, and made from oak wood. The length of sections between piers were not uniform but were determined by the varying lengths of timber available. The bridge was rebuilt in stone in the 14th century with arch piers around this wooden bridge, using it as a form of scaffolding, thus the arches are not uniform in width but vary in the same proportion as the wooden lintels of the original bridge. Two other traditional explanations for the varying spans exist. Firstly that each arch was funded by a different local guild and built piecemeal; secondly that the piers of the arches were built on naturally existing and therefore randomly situated large stones in the river. The existence of a bridge before that built or rebuilt traditionally by Sir Theobald Grenville is confirmed by a bequest of 40 shillings in the will of Bishop of Exeter Walter de Stapledon (d.1326) for the maintenance of Bideford Bridge.
The stone original of the present arched bridge is said by the Devon biographer John Prince, (1643–1723) to have been built in the 14th century and chiefly financed, according to Prince, by Sir Theobald II Grenville (d. circa 1377), lord of the manors of Bideford and of Stowe in Cornwall, and father of Sir Theobald III Grenville. Sir Theobald Grenville II was the son and heir of Henry de Grenville, and was aged 4 at the death of his father when he was granted in wardship to Sir John Carew. He was knighted on attaining his majority aged 21, and was, according to Granville (1895) but not supported by other sources, Sheriff of Devon in 1347. He married Joyce Beaumont, according to Granville (1895), daughter of Thomas Beaumont, Earl of Mellant (sic), perhaps Count of Meulan. The bridge was probably built during his minority.