Nico Ditch is a six-mile (9.7 km) long linear earthwork between Ashton-under-Lyne and Stretford in Greater Manchester, England. It was dug as a defensive fortification, or possibly a boundary marker, between the 5th and 11th century. The ditch is still visible in short sections, such as a 330-yard (300 m) stretch in Denton Golf Course. For the parts which survived, the ditch is 4–5 yards (3.7–4.6 m) wide and up to 5 feet (1.5 m) deep. Part of the earthwork is protected as a Scheduled Ancient Monument.