Route: Devil's Ditch (UK)

An ancient earthwork raised wall and fosse of unknown origin, but estimated to be at least 1400 years old as an Anglo-Saxon barrier between the kingdoms of East Anglia and Mercia. Spanning Reach on the N.W. terminus and Woodditton on the S.W. terminus. 

Undulating compacted chalky earth underfoot starting in dense forest and thick mud at the South, eventually opening up to expansive and more dry chalk at the North as it gradually descends to the fen-border village of Reach. 

Historical survey link:
https://www.british-history.ac.uk/rchme/cambs/vol2/pp139-147