Nico Ditch (occasionally Mickle Ditch or Nikker) is a six mile (9.7 km) long linear earthwork running between Ashton-under-Lyne and Stretford in Greater Manchester, England. It may have been dug as a defensive fortification, but more likely it was intended to be a boundary marker. It was constructed some time between the 5th and 11th centuries AD. In the parts which survive, the ditch is 3–4 metres wide and up to 1.5 metres deep. Part of the earthwork is protected as a Scheduled Ancient Monument. Nico Ditch stretches six miles (9.7 km) from Ashton Moss (grid reference SJ909980) in Ashton-under-Lyne to Hough Moss (grid reference SJ82819491), just east of Stretford. It passes through Denton, Reddish, Gorton, Levenshulme, Burnage, Rusholme, Platt Fields Park in Fallowfield, Withington, and Chorlton-cum-Hardy, crossing four metropolitan boroughs of present-day Greater Manchester. The ditch coincides with the boundaries between the boroughs of Stockport and Manchester, and between Tameside and Manchester as far as Denton golf course. A section is now beneath the Audenshaw Reservoirs, which were built towards the end of the 19th century. The ditch may have extended west beyond Stretford, to Urmston (grid reference SJ78299504).