Hounslow Heath is a local nature reserve in the London Borough of Hounslow and at a point borders Richmond upon Thames. The public open space, which covers , is all that remains of the historic Hounslow Heath which covered more than . The present day area is bounded by A315 Staines Road, A3063 Wellington Road South, A314 Hanworth Road, and the River Crane. History The heathland of Hounslow Heath originally covered an area underlain by Taplow gravel that now includes parts of Bedfont, Brentford, Cranford, Feltham, Hampton, Fulwell, Hanworth, Harlington, Harmondsworth, Heston, Hounslow, Isleworth, Stanwell, Teddington, Twickenham, and Heathrow. Hounslow Heath has had major historical importance, originally crossed by main routes from London to the west and southwest of Britain. Staines Road, the northern boundary of the present heath, was the Roman Road, Via Trinobantes. There are several historic references to Roman camps on or close to the heath. Continuous recorded history dates back to Norman times. In 1546, Hounslow Heath was surveyed with a recorded area of (6.71 square miles). Various armies used the heath due to its proximity to London, Windsor and Hampton Court. Oliver Cromwell stationed an army there at the end of the English Civil War in 1647. James II camped his army there, and conducted military exercises and mock battles to try to intimidate the population in London. In 1793, Hounslow Barracks was built to the north of Staines Road as part of the preparations to meet a possible French invasion. In the 17th and 18th centuries, the heath was notorious as the haunt of highwaymen and footpads, being crossed by the Great West Road and the Bath Road. The eventual mapping of the whole of the United Kingdom by the Ordnance Survey began with the measuring of an accurate base-line on Hounslow Heath, chosen for its flatness and its relative proximity to the Royal Greenwich Observatory. A sighting was made of the spire of All Saints' church in Banstead, and along that line a length of 27,400 feet was very precisely measured. This work by General William Roy was the start of the Anglo-French Survey (1784–1790), which led to the Principal Triangulation of Great Britain. By 1900, the heath was still in use as a training ground for horse-mounted cavalry based at Hounslow Barracks, a gun shooting range, and adjacent army medical units including an isolation hospital. After the outbreak of World War I