At 317 yards, Charlton Viaduct is the longest of seven on the Evercreech Jnc-Bath section of the Somerset & Dorset Railway. It is notable for being lower at its midpoint than at either end - the line falling on a 1:55 gradient from both ends. It lies on a curve of 30 chains radius and is formed of 27 arches, each with a 28-foot span. At its highest point, it reaches 45 feet,
The original single track structure was built of rubble limestone with brick segmental arches but this was widened, mostly in brick, by 15 feet on its western side in 1892 when the Shepton Mallet-Binegar section was doubled.
Charlton Viaduct is effectively split into three equal sections, separated by king piers. These also include a pilaster. Every third pier is buttressed to act against the forces created by the structure's curvature.
Opened in 1874, the viaduct carried its last train in 1966 although it became the subject of a Grade II* listing 14 years earlier. Today it serves as the unusual backdrop to a public garden at the east side of Shepton Mallet.