Berkhamsted is situated 26 miles (42 km) northwest of London within the Chiltern Hills, part of a system of chalk downlands throughout eastern and southern England, believed to have formed between 84 and 100 million years ago in the Cretaceous Period when the area was a chalk-depositing marine environment.
The town is located in a narrow northwest to southeast valley falling from 590 feet (180 m) above sea level to 344 feet (105 m).
The valley is at the southernmost limit of the Pleistocene glaciation ice erosion throughout the Chiltern scarp, giving it a smooth rounded appearance, with alluvial soils in the valley bottom and chalk, clay and flint on the valley sides.
In the early Mesolithic period (Middle Stone Age, mid to late 8th millennium BC), the local upland was mostly pine woodland and the low area of central Berkhamsted probably a grass-sedge fen.
In the 6th Millennium BC the dense deciduous forest became well established.
By the Mid to late 3rd millennium BC during the Neolithic period (the New Stone Age) human activity can be seen in wood clearances; the woodland being then dominated by lime trees, with alder trees growing on the flood plain.
The River Bulbourne, a chalk stream, runs through the valley for 7 miles (11 km) in a southeast direction, starting at Dudswell and the adjoining village of Northchurch and running through Berkhamsted, Bourne End and Boxmoor, where it merges with the River Gade at Two Waters in Apsley, near Hemel Hempstead.
Rich in eels and other fish, it was fast-moving and full, and prone to frequent localised flooding.
The river created a marsh environment (at times referred to as an 'unhealthy swamp') in the centre of the valley.
 The river powered the watermills (recorded in 1086) and fed the three moats of the large Norman Motte and Bailey castle, that stands close to the centre of the town where a small dry combe joins the Bulbourne valley.

The countryside surrounding the town includes parts of the Green Belt and the Chilterns Area of Outstanding Natural Beauty.
The Urban Nature Conservation Study (UNCS) recognises the town's hinterland as a biodiversity resource.
The hills gently rise to an undulating and open plateau, which has a mix of arable farmland, common land and mixed oak, ash and beech woodland.
On the northeast side of town are the Berkhamsted and Northchurch commons, the largest in the Chilterns at 1,055 acres (427 ha), and forming a large arc running from Northchurch, through Frithsden and down to Potten End.
Ownership of Berkhamsted Common is divided between the National Trust and Berkhamsted Golf Club.
Beyond the common is the 5,000-acre (2,000 ha) historic wooded parkland of Ashridge; once part of Berkhamsted Castle's hunting park, it is now managed by the National Trust.
Ashridge is part of the Chilterns Beechwood Special Area of Conservation (SAC), a nationally important nature conservation area, and is also designated as a Site of Special Scientific Interest.
Agriculture is more dominant to the south of the town; close to the Buckinghamshire border there are two former large country estates, Ashlyns and Rossway.
The ancient woodland at Dickshills is also located here.

The layout of Berkhamsted's centre is typical of a medieval market settlement: the linear High Street (aligned on the Akeman Street) forms the spine of the town (roughly aligned east–west), from which extend medieval burgage plots (to the north and south).
The surviving burgage plot layout is the result of a comprehensive plan carried out at the beginning of the 13th century, most probably instigated by Geoffrey fitz Peter.
The town centre slowly developed over the years and contains a wide variety of properties that date from the 13th century onwards.
The modern town began to develop after the construction of the Grand Junction Canal in 1798.
The canal intersects the river at numerous points, taking most of its water supply and helping to drain the valley.
The locality became further urbanised when the London to Birmingham railway was built in 1836–37.
The townscape was shaped by the Bulbourne val
Berkhamsted is situated 26 miles (42 km) northwest of London within the Chiltern Hills, part of a system of chalk downlands throughout eastern and southern England, believed to have formed between 84 and 100 million years ago in the Cretaceous Period when the area was a chalk-depositing marine environment. The town is located in a narrow northwest to southeast valley falling from 590 feet (180 m) above sea level to 344 feet (105 m). The valley is at the southernmost limit of the Pleistocene glaciation ice erosion throughout the Chiltern scarp, giving it a smooth rounded appearance, with alluvial soils in the valley bottom and chalk, clay and flint on the valley sides. In the early Mesolithic period (Middle Stone Age, mid to late 8th millennium BC), the local upland was mostly pine woodland and the low area of central Berkhamsted probably a grass-sedge fen. In the 6th Millennium BC the dense deciduous forest became well established. By the Mid to late 3rd millennium BC during the Neolithic period (the New Stone Age) human activity can be seen in wood clearances; the woodland being then dominated by lime trees, with alder trees growing on the flood plain. The River Bulbourne, a chalk stream, runs through the valley for 7 miles (11 km) in a southeast direction, starting at Dudswell and the adjoining village of Northchurch and running through Berkhamsted, Bourne End and Boxmoor, where it merges with the River Gade at Two Waters in Apsley, near Hemel Hempstead. Rich in eels and other fish, it was fast-moving and full, and prone to frequent localised flooding. The river created a marsh environment (at times referred to as an 'unhealthy swamp') in the centre of the valley.  The river powered the watermills (recorded in 1086) and fed the three moats of the large Norman Motte and Bailey castle, that stands close to the centre of the town where a small dry combe joins the Bulbourne valley. 
The countryside surrounding the town includes parts of the Green Belt and the Chilterns Area of Outstanding Natural Beauty. The Urban Nature Conservation Study (UNCS) recognises the town's hinterland as a biodiversity resource. The hills gently rise to an undulating and open plateau, which has a mix of arable farmland, common land and mixed oak, ash and beech woodland. On the northeast side of town are the Berkhamsted and Northchurch commons, the largest in the Chilterns at 1,055 acres (427 ha), and forming a large arc running from Northchurch, through Frithsden and down to Potten End. Ownership of Berkhamsted Common is divided between the National Trust and Berkhamsted Golf Club. Beyond the common is the 5,000-acre (2,000 ha) historic wooded parkland of Ashridge; once part of Berkhamsted Castle's hunting park, it is now managed by the National Trust. Ashridge is part of the Chilterns Beechwood Special Area of Conservation (SAC), a nationally important nature conservation area, and is also designated as a Site of Special Scientific Interest. Agriculture is more dominant to the south of the town; close to the Buckinghamshire border there are two former large country estates, Ashlyns and Rossway. The ancient woodland at Dickshills is also located here.
The layout of Berkhamsted's centre is typical of a medieval market settlement: the linear High Street (aligned on the Akeman Street) forms the spine of the town (roughly aligned east–west), from which extend medieval burgage plots (to the north and south). The surviving burgage plot layout is the result of a comprehensive plan carried out at the beginning of the 13th century, most probably instigated by Geoffrey fitz Peter. The town centre slowly developed over the years and contains a wide variety of properties that date from the 13th century onwards. The modern town began to develop after the construction of the Grand Junction Canal in 1798. The canal intersects the river at numerous points, taking most of its water supply and helping to drain the valley. The locality became further urbanised when the London to Birmingham railway was built in 1836–37. The townscape was shaped by the Bulbourne val
Berkhamsted