The Trundle is an Iron Age hillfort on St Roche's Hill about 4 miles (6 km) north of Chichester, West Sussex, England.

Crawford obtained an aerial photograph of the Trundle, clearly showing additional structures inside the ramparts of the hillfort.

In 2011, the Gathering Time project published an analysis of radiocarbon dates from almost forty British causewayed enclosures, including some from the Trundle.

A review of the site in 1995 by Alastair Oswald noted the presence of fifteen possible Iron Age house platforms within the hillfort's ramparts.

[2] Causewayed enclosures are a form of earthwork that was built in northwestern Europe, including the southern British Isles, in the early Neolithic.

There is also evidence that they played a role in funeral rites: material such as food, pottery, and human remains was deliberately deposited in the ditches.

[9] The construction of an enclosure took only a short time, which implies significant organization since substantial labour would have been required for clearing the land, preparing trees for use as posts or palisades, and digging the ditches.

[10] Over seventy causewayed enclosures are known in the British Isles,[6] and they are one of the most common types of an early Neolithic site in western Europe.

[14] The summit on which both the causewayed enclosure and the hillfort stand is St Roche's Hill, an outcrop of the Upper Chalk that lies at the western end of a ridge.

[24] A linear cropmark outside the banks has not been excavated but archaeologist Alastair Oswald, who surveyed the site in 1995 for the Royal Commission on the Historical Monuments of England (RCHME), considered it to be no earlier than Iron Age.

[26] There are two dykes to the north, crossing two of the ridges that approach the hill; the eastern of these included a crouched burial, revealed when a carpark was constructed there, and thought to be dated to the Bronze Age, based on the presence of what appeared to be a round barrow.

A document from 1570 refers to it as "the late chapell of St Rooks", so it was apparently already in ruins by that date, probably having been abandoned or destroyed during the Reformation.

[28][29] In 1645, William Cawley reported in Parliament that a thousand Clubmen—one of several local militias formed to oppose the depredations of both sides in the English Civil War—had assembled on the hill.

[34] A windmill, which burned down in 1773, is known to have existed on the hill; Hadrian Allcroft, a historian, describes it as having been built "almost upon the ruins" of the chapel.

[37] A 1723 etching of the hillfort is included in William Stukeley's Itinerarium Curiosum (1776), and it is mentioned in Alexander Hay's 1804 History of Chichester: "... saint Roche's hill, commonly called Rook's hill; on the top of which are the remains of a small camp, in a circular form, supposed to have been raised by the Danes, when they invaded and plundered this country".

[38][39] An 1835 history of Sussex discusses the hillfort, giving reasons for doubting that it was Roman or Danish, and concluding that the builders could not be certainly determined.

The additional circular earthworks revealed inside the ramparts led Crawford to believe that the hillfort had been built on the site of a Neolithic camp.

To test this idea, Curwen obtained permission from the Duke of Richmond, who owned the land, and excavated the site between 7 August and 1 September 1928.

[47] The ditch cuttings found chalk rubble in the lowest layer, which Curwen took to be natural silt infill beginning with the original occupation of the site;[47] in Oswald's 1995 review he suggested it may have been deliberately filled.

[38] Above this was a layer with a very few Hallstatt and La Tène pottery sherds, but little else,[47][48] and Curwen proposed that this was deliberate infill by the Iron Age inhabitants who wished to level the site within the new hillfort's ramparts.

[47] The boundary between these two layers he suggested was the turf line that would have been the surface of the unoccupied site throughout the intervening Bronze Age.

There was no evidence that allowed direct dating of this layer, but Curwen suggested that the patination of the flint surfaces where they had been trimmed implied that they were laid by the Iron Age builders of the hillfort.

[54] The area where the outer Neolithic ditch met the northern Iron Age rampart was excavated, and here Curwen found a crouched burial of a woman, 25–30 years old and about 1.5 m (4 ft 11 in) tall.

[55][56] The skeleton lay below a small cairn of chalk, with the hole dug into the upper part of the Neolithic level, and the rampart at that point had been built after the burial.

[68] Four more pits were found and excavated; three in the area of the cuttings, and another inside the inner ditch; all contained Iron Age pottery sherds, including both Halltstatt and La Tène types.

He was unable to find a convincing interpretation for the holes, suggesting only that they might "represent a grandiose scheme of fortification which was begun shortly before the abandonment" of the hillfort.

[73] The Trundle was one of the sites included in Gathering Time, a project funded by English Heritage and the Arts and Humanities Research Council to reanalyze the radiocarbon dates of nearly 40 causewayed enclosures, using Bayesian analysis.

A carpark redevelopment proposal led to a 1994 excavation with four trenches that discovered small amounts of prehistoric pottery and flints.

A detailed survey of the site was made by the RCHME in 1995, covering both the hillfort and the causewayed enclosure, with the resulting report authored by Alastair Oswald.

[78] In June/July 2010, The Trundle was temporary host to Artemis, a 30 ft tall bronze sculpture of a horse designed by sculptor Nic Fiddian-Green.