The Slad is the name given to an Iron age

Iron Age

The Iron Age is the archaeological period generally occurring after the Bronze Age, marked by the prevalent use of iron. The early period of the age is characterized by the widespread use of iron or steel. The adoption of such material coincided with other changes in society, including differing...

 defensive earth rampart

Defensive wall

A defensive wall is a fortification used to protect a city or settlement from potential aggressors. In ancient to modern times, they were used to enclose settlements...

 in Hertfordshire

Hertfordshire

Hertfordshire is a ceremonial and non-metropolitan county in the East region of England. The county town is Hertford.The county is one of the Home Counties and lies inland, bordered by Greater London , Buckinghamshire , Bedfordshire , Cambridgeshire and...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. It is thought to have formed part of a larger defensive fortification, joining up with Beech Bottom Dyke

Beech Bottom Dyke

Beech Bottom Dyke, is a large ditch running for half a mile at the northern edge of St Albans, Hertfordshire flanked by banks on both sides. It is up to wide, and deep, and it can be followed for half a mile between the "Ancient Briton Crossroads" on the St Albans to Harpenden road until it is...

 and the Devil's Dyke

Devil's Dyke, Hertfordshire

Devil's Dyke is the remains of a defensive ditch around an ancient settlement of the Catuvellauni tribe of Ancient Britain. It lies at the east side of the current village of Wheathampstead, Hertfordshire, England...

 and bordered on the other side by the River Lea and the River Ver

River Ver

The Ver is a river in Hertfordshire, England. The river begins in the grounds of Markyate Cell, and flows south for 12 miles alongside Watling Street through Flamstead, Redbourn, St Albans and Park Street, and joins the River Colne at Bricket Wood....

 to create a fortified enclosed settlement of approximately 35 hectares (86 acres).

It was constructed towards the end of the Iron Age

Iron Age

The Iron Age is the archaeological period generally occurring after the Bronze Age, marked by the prevalent use of iron. The early period of the age is characterized by the widespread use of iron or steel. The adoption of such material coincided with other changes in society, including differing...

, and probably in the early 1st century AD. This, and other similar earthworks in the district, were built by the powerful Celtic tribe established in this area, the Catuvellauni

Catuvellauni

The Catuvellauni were a tribe or state of south-eastern Britain before the Roman conquest.The fortunes of the Catuvellauni and their kings before the conquest can be traced through numismatic evidence and scattered references in classical histories. They are mentioned by Dio Cassius, who implies...

, to define areas of land around their tribal centre at Verlamion

Verlamion

Verlamion, or Verlamio, was the tribal capital of the Catuvellauni tribe in Iron Age Britain from approximately 20 BC until shortly after the Roman invasion of 43 AD...

 - the predecessor of the Roman city of Verulamium

Verulamium

Verulamium was an ancient town in Roman Britain. It was sited in the southwest of the modern city of St Albans in Hertfordshire, Great Britain. A large portion of the Roman city remains unexcavated, being now park and agricultural land, though much has been built upon...

.

Unlike Beech Bottom Dyke and Devil's Dyke, the Slad is located on private property, and is not accessible to the public.