The bridge is situated at a point where the Llangollen feeder branches off from the Ellesmere Canal (renamed Llangollen Canal, 1963) at the south-eastern corner of the Trevor Basin near the north end of the Pontcysyllte Aqueduct.

This is one of the three most important bridges on the Ellesmere Canal (the other two are the second overbridge at Trevor Basin and the former A5 overbridge at Chirk Bank) in having one of the earliest uses of cast-iron in a canal overbridge anywhere and for that reason is of international importance.

Cambered cast-iron girders support ashlared stone voussoirs to form a flattened arch carrying ashlared parapets with stone sills and capping. Parapet wings curve downwards and outwards on both sides, terminating in piers with pyramidical caps. Abutments in rubble sandstone with ashlared quoins. Rubble walls (probably later) continue beyond at both ends on E side.

The canal bridge was built in 1804-08 to carry a road over the navigable Llangollen water feeder. An Act to construct the Ellesmere Canal, linking the Dee, Mersey and Severn Rivers, was passed in 1793. When, however, it was decided in 1801 not to continue the canal beyond Pontcysyllte a 9.656km long feeder canal (taking water from the Dee at the Horseshoe Falls) was proposed in order to supply water to the main canal. The feeder canal was constructed under the direction of Thomas Telford (general agent) and Thomas Denson (resident engineer); work was begun in 1804 and completed in 1808. In addition the canal provided transport to the slate quarries and limestone works. In 1846 it became part of the Shropshire Union Railways and Canal Company, but the following year was taken over by the London & North Western Railway. Transport on the canal diminished in later C19 with arrival of the railways and ceased by World War II. The canal was only kept open because of its importance as a supplier of water and has now became a major tourist asset.

Stephen R. Hughes 29.05.2007, account based on Cadw record number 19969.