Grim's Ditch, Harrow

Grim's Ditch is a linear earthwork in the London Borough of Harrow, Middlesex, extending approximately 6 miles (9.7 km) east-west from Stanmore to Pinner Green.[1] Thought to have been constructed by the Catuvellauni tribe in the 1st century AD as defense against Roman invasion, it crowns a gentle escarpment marking the historic border between Middlesex and Hertfordshire.[1] Today, visible earthworks survive along Harrow Weald Common.[1]