district, administrative and historic county of Wiltshire, southern England, located in the northwestern part of the county some 20 miles (32 km) east of Bristol. North Wiltshire bestrides the upper reaches of the Avon river valley. It is a fertile clay plain extending into the Cotswold Hills on the west and bordered by the steep chalk escarpment of the Marlborough Downs on the east; in the north is a headwaters area for many watercourses, including the Thames.

Many churches of the district date from before 1500, and about 500 buildings are officially listed as being of historical importance. The nearby Cotswolds are a source of oolitic limestone used in the construction of many of the district's buildings. Lacock, in the southern part of the district, is one of England's prettiest villages, with winding streets, gabled roofs, and timbered buildings. Its 13th-century abbey is well preserved, and a local museum (opened 1975) commemorates the pioneer photography of William Henry Fox Talbot.

Wheat and barley are intensively raised in North Wiltshire, as are cattle, sheep, and pigs. Malmesbury and Wootton Bassett are local market centres. Calne has a bacon-curing industry, and Chippenham, the district seat, has agricultural and railway-related industries. Area 296 square miles (766 square km). Pop. (2001) 125,372.