The racecourse at Chester is 65-acre (260,000 m2) in extent and lies on the banks of the River Dee. This was once a harbour during the Roman settlement of the city but was abandoned as the river silted up and navigation became impossible. Towards the centre of the in field is a raised mound which is decorated by a small cross known as a "rood". It is from this that the race course derives the name "Roodee"; Roodee is a corruption of "Rood Eye", meaning "The Island of the Cross".
Legend has it that this cross, only remains now, marks the burial place of a statue of the Virgin Mary. The statue was sentenced to death after being found guilty by a jury of twelve men following the death of Lady Trawst, the wife of Sytsylht, the Governor of Hawarden, a village in Wales.
The Lady's death is recorded thus:-
In the sixth year of the reign of Conan, 804AD, King of North Wales, there was in the Christian Temple at a place called Harden a Roodloft in which was placed an image of the Virgin Mary, with a very large cross, which was in the hands of the image, called Holy Rood. About this time there happened a very hot and dry summer; so dry that there was not grass for the cattle; upon which most of the inhabitants went and prayed to the image or Holy Rood, that it would cause it to rain, but to no purpose. Among the rest, the Lady Trawst (whose husband's name was Sytsylht, a nobleman and governor of Harden Castle) went to pray to the said Holy Rood, and she praying earnestly and long, the image or Holy Rood fell down upon her head and killed her; upon which a great uproar was raised, and it was concluded and resolved upon to try the said image for the murder of the said Lady Trawst, and a jury was summoned for this purpose. The Jury found the Holy Rood guilty of wilful murder, and the sentence was proposed that she should be hanged. This was opposed by some, who suggested that, as they wanted rain, it would be best to drown her. This, again, was objected to by others, who advised to lay her on the sands of the river and see what became of her. This was done, with the result that the image was carried by the tide to some low land near the wall of Caerleon (maybe Chester) where it was found by the Cestrians drowned and dead, and by them buried at the gate where found.
Also:- her [Lady Trawst's] prayers were answered by a tremendous thunderstorm whereupon the statue was loosened and fell, killing her. As a holy object, hanging or burning the statue would be sacrilege so the statue was left by the banks of the river and the tide carried it down to Chester.
In an alternate version of the legend, the statue was instead carried to St John's church. An ancient statue of the Virgin was recorded at the time of the reformation but may not be the same one. The statue was thrown down as a relic of popery, used as a whipping post for scholars and burned.
The cross was at one time removed and lay beneath the City Walls for many years. It was re-erected in its original position 1855 and is now Grade II* listed. The listing records: This is a base and part shaft of a stone cross. It is traditionally believed to be Saxon, but more probably a boundary stone, C13th, of land belonging to St Mary's Priory (which is no longer standing) which stood between Chester Castle and the Roodee. It is of sandstone. The base-stone is just above ground level and is a low, eroded, rectangular plinth, on this a damaged square shaft.
Information from Wikipedia Chester Racecourse
and Bytes, and one picture from Bytes
and the listing in 'British Listed Buildings' Roodeye