Wiltshire (or the County of Wilts) is a ceremonial county in South West England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and West Berkshire. It contains the unitary authority of Swindon and covers 3,485 km² (1,346 square miles). The ancient county town was Wilton, but since 1930 Wiltshire County Council and its successor Wiltshire Council (from 2009) have been based at Trowbridge.

Wiltshire is characterised by its high downland and wide valleys. Salisbury Plain is famous as the location of the Stonehenge and Avebury stone circles and other ancient landmarks and as the main training area in the UK of the British Army. The city of Salisbury is notable for its mediaeval cathedral. Important country houses open to the public include Longleat, near Warminster, and the National Trust's Stourhead, near Mere.