Wiltshire is the county for white horses. There are or were at least twenty-four of these hill figures in Britain, with no less than thirteen being in Wiltshire, and another white horse, the oldest of them all, being just over the border in Oxfordshire. Most of the white horses are chalk hill carvings, and the chalk downs of central Wiltshire make it an ideal place for such figures.
Of the thirteen white horses known to have existed in Wiltshire, eight are still visible, and the others have either been lost completely, or are in a sense still there, under the turf, but have long since become grown over and are no longer visible.
Contrary to popular belief, most white horses are not of great antiquity. Only the Uffington white horse is of certain prehistoric origin, being some three thousand years old. Most of the others date from the last three hundred years or so, though the hillside white horse can be a slippery creature, and the origins of some are impossible to establish with any certainty.
The
www.wiltshirewhitehorses.org.uk website concentrates on the Wiltshire horses, but aims to include all known hillside white horses in Britain and elsewhere, and includes some which are not chalk hill carvings but have been created by other methods. It does not cover hill figures other than white horses.
Go check out the fasinating site of Wiltshires historical chalked four legged friends of Britain.
The Uffington horse is around three thousand years old, having been dated to between 1400 - 600 BC:

There are many stories that King Arthur is not dead, but lies sleeping, and will one day awake when England is in peril. (Why he should help the descendants of those he fought is a question that shall not be entered into here!) It is said locally that when Arthur awakes, the Uffington horse will rise up and dance on nearby Dragon Hill.
Source: wiltshirewhitehorses.org.uk
Picture: Wikipedia (copyright free)