The Church of St. Nicholas on lower Westgate Street has its origins as an early-12th century royal foundation, though it does not appear in the documentary record until 1180. In its initial incarnation, the church comprised nave, chancel and north aisle.
It was during the 12th century that the River Severn shifted, cutting a new channel across the ancient road west out of Gloucester. This made it necessary for the first time to construct a new bridge which, over the course of the next eight centuries, evolved into today's Westgate bridges. The church was given custody of the new bridge, and by 1203 it was known as St. Nicholas of the Bridge of Gloucester. In 1229 King Henry III gifted the church to St. Bartholomew's Hospital, the late-18th century successor of which is now a retail premises lining the approach to the Westgate bridges.
In the 13th century, perhaps because of the association with St, Bartholomew's, the original Norman church was substantially rebuilt. Two bays of the north aisle, a carved tympanum (a semi-circular decorative wall) above the entrance and, according to one source, the south wall are the only surviving remnants of the 12th-century structure. In 1347 a porch was added, originally with a room above, and the same year a west bell tower was recorded. In the 14th and 15th centuries, windows in the newly fashionable Perpendicular style were installed along the south aisle. The tower and spire we see today were built in the early-15th century, and at the same time the north aisle was rebuilt and extended alongside the new tower. The smaller entrance at the east end of the south aisle was added in 16th century, and in the 17th century the north-east corner was rebuilt.
Meanwhile, both hospital and church passed in 1564 into the auspices of Gloucester Corporation (which in 1974 became Gloucester City Council). The church remained closely associated with the hospital and was was described as a free chapel annexed to the hospital in the 18th and 19th centuries. In 1871 the church passed from Corporation to the Diocese of Gloucester. The 19th century saw the beginning of a huge shift in the demographics of Gloucester. Expansion into new suburbs resulted in a declining city-centre population and a consequent dwindling congregation. The benefice was merged with St. Mary de Lode in 1951, and the Church of St. Nicholas was closed in 1967. It was in the redevelopments of the 1960s that the residents of the church graveyard – which had occupied Saxon plots on the north side of the church, but which had ceased to be used for burials in 1854 on the opening of the Corporation cemetery at Tredworth – were relocated and the land sold to accommodate a wing of the Archdeacon flats.
The ground on which the church is built, still close to the Severn but closer still when the Old Severn still flowed, is somewhat marshy. This has caused a problem with subsidence and given the church a pronounced lean, clearly visible from the inside. The fortunes of the church, which had once been the wealthiest parish in Gloucester, were in decline in the 17th and 18th centuries. Such was the state of the structure that fittings were removed, services were temporarily suspended and a petition was presented in 1786 to demolish the church and rebuild it on another site. The perilous state of the spire, which leans two-and-half feet (three quarters of a metre) from the vertical, was a particular cause of concern. Being struck by royalist artillery during the siege of Gloucester in 1643 had probably not done much to help. In 1783 the spire was truncated significantly "for fear of its tumbling" and topped with a copper coronet.
A survey in 1787 concluded that the church was not actually in imminent danger of collapse, and repairs and restorations followed at the end of the 18th century, then in 1843, 1865 (during which the main porch was rebuilt) and, following a fire, in 1901. Around 1925–1926 the foundations were shored up with some thirty tons of concrete. Further work in 1935–1938 re-roofed the church and rebuilt the north aisle.
The church, which remains consecrated to this day, passed into the care of the Churches Conservation Trust in 1975. It has been listed Grade I by Historic England since 1952. Sadly, because of the poor condition of a roof that is now end-of-life, the church is one of Gloucester's residents in the Historic England Heritage At Risk Register. Although the property is locked, keys are held by Brimbles Cafe farther up Westgate Street and, just across the street, the Folk of Gloucester. It is also a regular participant in the annual Heritage Open Days.