Medieval and post-medieval single span bridges are structures usually designed to carry a road or track over a river by means of a single arch, typically 3m-6m in span. They were constructed for the use of pedestrians and packhorse or vehicular traffic. Stone or brick bridges constructed from the medieval period onwards were built with pointed, semicircular or segmental arches. The bridge abutments and revetting of the river banks also form part of the bridge. The theory and practice of masonry construction for bridges reached a high point in the 18th century. After this time increasing demand led to quicker builds with the adoption of iron bridges and later metal truss bridges.
Despite later alterations, Three Colt Bridge survives well with some impressive cast iron architectural features. The bridge is a significant element of the historic fabric of the Hertford Union Canal.
The monument includes an early 19th century single span bridge over the Grand Union Canal. It is situated on low-lying ground on the south-east side of Victoria Park in Hackney.
The bridge has a slightly cambered cast iron girder deck with an open geometric iron parapet railing on the east side and iron mesh screen on the west side. The bridge abutments are of stock brick with stone quoins. At either end of the bridge are brick wing walls with a brick band and stone coping. The bridge surface is of concrete topped with asphalt. The brick work on the canal towpath exhibits historic wear patterns relating to 19th century rope marks caused by horses towing canal boats.
Three Colt Bridge was built in 1830 and is contemporary with the opening of the Hertford Union Canal. The Hertford Union Canal was instigated by Sir George Duckett and constructed by Francis Giles. It spanned 2km from the Regent's Canal to the Lee Navigation. It was later bought by the Regent’s Canal Company before it joined the Grand Union system in 1929. At the northern edge of the bridge is Victoria Park, a Grade II* registered park.