Parishes is at its highest in the chalk hills in the northwest of the area, generally sloping down towards the southeast. The whole area lies between 100 and 500 feet (30 and 150 metres) above sea level. There are no major rivers but the many small ones follow valleys that give the area its attractive, gentle landscape. In the west, the rivers Rib, Ash and Stort flow south from the Hundred Parishes to meet the Lea and then the Thames. In the east, the Chelmer and Pant flow from the Hundred Parishes into the Blackwater and then the North Sea. The Cam flows northwards through the middle of the northern half of the Hundred Parishes, gathering up the Granta and Rhee before leaving the Hundred Parishes bound for Cambridge and the North Sea. And in the south, the Roding, which gives its name to several villages in the Hundred Parishes, flows south to meet the Thames at Barking Creek. Features and attractions Many of the area's individual parishes appear in the Domesday Book of 1086 and there is considerable evidence of earlier settlements. Relics from the Iron Age and Bronze Age have been found in a number of locations. Roman roads including Stane Street and Ermine Street cross the Hundred Parishes. An ancient long-distance trackway, the Icknield Way, which may pre-date the Roman roads, passes from west to east through the northern part of the area. Saffron Walden is the area's largest settlement, with a population of 17,000 in 2021. It has been a market town since the 12th century. There are three more market towns: Buntingford, Great Dunmow and Thaxted. Most of the area's villages have a historical church, a pub and a village green, and most are within easy walking distance of the next settlement. Individual visitor attractions include Audley End House, a Jacobean mansion now cared for by English Heritage, and Hatfield Forest, a medieval royal hunting forest now within the care of the National Trust. The area has several small museums and galleries. Architecture The Hundred Parishes has over 6,000 listed buildings, an especially high number for its population of around 150,000 – around 5 times the average ratio of listings to population for England as a whole. Of these listings, 106 are Grade I, including 60 churches. Typical architectural features include timber-framed buildings, flint (especially for churches), thatched roofs, whitewashing and/or pargeting on external walls.