Off Aylestone Road in Leicester, a low earthwork survives as one of the city’s most unusual Roman relics. Raw Dykes (grid reference SK583026) is a scheduled monument consisting of two parallel banks up to 20 metres apart, with an excavated channel running between them. Of an original length of at least 550 metres, only a 110-metre stretch now remains, the rest having been swallowed by the expansion of Leicester over the centuries. The public cannot walk the site freely, but a viewing enclosure off Aylestone Road allows visitors to observe what survives.
An Aqueduct, a Canal, or Something Else?
The official schedule of monuments maintained by the Department of Culture, Media and Sport records Raw Dykes as a Roman aqueduct. The narrow cut running along the centre of the ditch is understood to have been the main water channel, designed to concentrate flow within a confined space and increase its speed. A Leicester City Council publication raised the possibility that the earthwork may instead have been a canal, though it concluded that the aqueduct interpretation is by far the most likely explanation. The debate does not end there: archaeologist Kathleen Kenyon argued that the structure follows the modern 60-metre contour, placing it lower than the Roman bath in Leicester, which would make it ineffective as a water supply. J.S. Wacher countered that Roman engineers were highly capable hydraulic builders, and that water may well have been pumped uphill into the town. Evidence of a pump and a storage tank at Leicester’s Roman baths, dating to the 4th century AD, lends some support to this view.
History and Age
Excavations carried out in 1938 uncovered two Roman pottery sherds from the 1st century AD, placing the construction of Raw Dykes no earlier than that period. The first written mention of the earthwork appears in the borough of Leicester’s financial accounts from 1322. During the English Civil War, Royalist soldiers made use of part of the structure as an artillery emplacement. The monument also appears on a number of 18th- and 19th-century maps, reflecting its visibility in the pre-industrial city. Urban growth since the early modern period has removed the greater part of the original earthwork, leaving the surviving stretch as the only physical evidence of what was once a substantial Roman engineering project.