Not far from the village lies the route of one of those typically ambitious building feats of the industrial revolution. The Thames and Severn Canal was completed in 1789. Conceived as part of a canal route from Bristol to London, at its eastern end it connects to the River Thames at Inglesham Lock near Lechlade, while at its western end it connects to the Stroudwater Navigation (which links Stroud with the Severn) at Wallbridge near Stroud. There is a short branch from Siddington to Cirencester. When built, it included at Sapperton the longest canal tunnel in Britain (it remains the third longest to this day, the two longer being at Standedge in the Pennines and at Strood in Kent). The canal was not a great success: as no reservoirs were built, water supply was erratic, while the summit section near the tunnel ran through porous limestone, which brought constant leakage. Competition from the railways took much of the canal's traffic by the end of the 19th century, and most of the canal was abandoned in 1927, the remainder in 1941. The builders of the Thames and Severn canal and the Great Western railway undertook major engineering works to negotiate a route through the parish beneath Sapperton Hill. The canal, which was completed as far as Daneway wharf in 1786 (the wharf was equipped with a warehouse and coalyard), entered Sapperton Hill half a mile to the east of the wharf. Work on the tunnel, 3,817 yards in length, began in 1784 and was completed in 1789. The western portal of the tunnel (see below for location) is in the Gothic style with pinnacles and castellations; the eastern portal (at Coates) is more grandiose, in classical style. The last boat passed through the tunnel in 1911 and the section of the canal east of Whitehall bridge in the Golden Valley was abandoned in 1927, the section to the west of the bridge being abandoned in 1933.
Because of the costs involved, the Sapperton tunnel did not have a towpath. Instead, before the invention of the steam engine, leggers were employed to manoeuvre the barges through the tunnel. Two people were required. They would lie on a plank across the bows of the boat, and holding the plank with their hands, would propel the boat with their feet against the tunnel wall. This was a dangerous procedure. The horse, meanwhile, would be lead to the other end of the tunnel, where it would meet the boat and resume its haulage.
Across the bridge in Bisley parish stood the Daneway Inn, a house built originally to lodge the navvies working on the tunnel and converted for use as a public-house by 1807 when it was called the Bricklayers' Arms, a name it retained until the mid 20th century. A short walk (15 minutes) from Sapperton, passing the old tunnel entrance and along the towpath, brings you there.
From the church in Sapperton, walk down a path beside it until you come to agate at afield. Go in and turn left. Follow an obvious path across the field and down the valley to a stile at some trees. This leads you directly onto what seems like an exotic bridge but which, once you descend onto a path on the far side, is in fact the parapet of the historically important tunnel. On the far side turn right to walk along the old canal path until you reach the pub at Daneway. Return the same way – or continue further on the other side of the road, to come to a series of derelict canal locks.