Crossing the River Dee a half-mile (0.8 km) southwest of Tongland and 1¼ miles (2 km) north of Kirkcudbright, the Tongland Bridge was designed by noted engineer Thomas Telford (1757 - 1834) although the aesthetic treatment, involving castellated towers and a corbelled-out parapet, was the work of Alexander Nasmyth (1758 - 1840).
Constructed between 1804-08 the bridge comprises a 34-m (112-feet) main span with side spans each supported on three Gothic pointed arches. It was the first bridge in Britain to carry a road on spine walls rising from the arch rings. The bridge was strengthened in the middle of the 20th century.
A bridge was begun here in 1803, but the span proved too great and the partial construction was destroyed by floods within a year. Telford was brought in and proposed a more substantial structure, although this was to cost more than twice the price of the original.