These two earth banks with a ditch between, to be found beside the Aylestone Road, are all that remains of a water course that brought supplied the Roman city of Leicester.
The Eccentric Leicester Tour on the University of Leicester's website says:
The current earthworks are a fragment of very much larger works. The surviving stretch of the Raw Dykes is about 100 metres of linear earthworks comprising two parallel earthen banks (double vallum) with a channel (Fosse) measuring about 6 metres between them. The height of the bank varies between 4 and 7 metres.
The earliest known documentary reference to the earthworks is contained within the Lord Mayor's accounts for the Borough of Leicester of 1322 which refer to the 'Rowedick'. The etymology is considered to suggest that the name was originally derived from the linearity of the earthworks, the present form 'Raw Dykes' representing a corruption of this.
Excavations in 1938 recovered pottery suggesting that the earthworks were constructed during or immediately after the first century AD and consisted of banks defining a broad ditch within which was a much narrower central channel. The layout and nature of the earthworks are considered to suggest that the narrow cut within the centre of the ditch represented the main water channel and was designed to increase the flow of water by concentrating it within a constricted space.To view the Raw Dykes you have to make your way down a path to a little viewing area, surrounded all the time by chain-link fencing.