Port Way (also known as the Portway) is an ancient road in southern England, which ran from Calleva Atrebatum (Silchester, in modern-day Hampshire) in a south-westerly direction to Sorbiodunum (Old Sarum, Wiltshire). Often associated with the Roman Empire, the road may have predated the Roman occupation of Britain. Margary's Roman road numbering system, devised in the 1950s, gave the route from Londinium to Isca Dumnoniorum the number 4; the Port Way section is 4b. He recorded the distance of this section as 36+1⁄4 miles (58.3 km).