The remains of a volcano that erupted under water during the Carboniferous period, Arthur's Seat is located within Holyrood Park in the centre of Edinburgh. Although only 250m (823 feet) in height, Arthur's Seat is a notable landmark, dominating the city. Known also as the Lion's Head, Arthur's Seat is the highest of a series of peaks which take the form of a crouched lion. Its summit is marked both by a white Ordnance Survey triangulation pillar and a geographical indicator. The indicator gives directions to prominent surrounding landmarks and is a replacement for the original positioned here in 1910, which was cast in bronze and designed by the noted surveyor John Mathieson (1855 - 1945).
Geologically Arthur's Seat comprises the remains of a basalt lava plug that choked the neck of a volcano which would have been active around 335 million years ago. The action of glaciation has cut into its heart, making it one of the most accessible exposures of an ancient volcano.
Two stony banks on the east side of the hill represent the remains of an Iron-Age hill fort and a series of cultivation terraces are obvious above the road just beyond. In 1836, just below the summit, seventeen miniature wooden coffins each containing a carved figure were found in a small cave. Their existence has never been satisfactorily explained; associations with witchcraft have been suggested or perhaps they were memorial to the seventeen victims of the infamous William Burke (1792 - 1829) and William Hare (died c.1860).