Waddon Hill is a hill and the site of a short-lived Roman fort near Beaminster, in the English county of Dorset. The name Waddon is from the Old English, meaning wheat hill.

The Wessex Ridgeway passes to the north of the hill summit and Roman fort. The B3162 road passes close to the western end of the hill. Lewesdon Hill is about 0.6 miles (1 km) to the west.

There is no public right of way on the summit of Waddon Hill, although local people often walked on the hill for centuries, until a change of ownership in the 21st century, and the need to protect the site from illegal detecting.

The fort is on a narrow east-west ridge reaching a height of 210 m, with steep natural slopes to the south and west, and linear ramparts facing north and east.

The fort was built by the Second Legion under Vespasian, but after the occupation of Dorset. Though it is conjectured that the fort originated as a temporary camp during the campaign against nearby Pilsdon Pen, Pilsdon Pen was almost certainly abandoned before the invasion, and the claimed Roman ballista bolt on display in Dorchester museum is too large to be a ballista bolt. There is a recently (2017) discovered much larger fort at Bradford Abbas, likely to be the main early fort in the area.

First recognition of the site came when 19th century quarrying uncovered military artefacts from the 1st century AD. James Ralls, a Bridport ironmonger and a Mr Powlesland worked at the site in 1878 to 1882, with a detailed article written by the Shakespearian scholar Boswell-Stone, whose father was born in Stoke Abbott, given as a lecture at the Bridport Literary Institute in 1892. The Ralls collection of material passed to the Colfox family, who donated it to the Bridport Museum in the 1930s. The residual items collected by Powlesland were auctioned by Sotheby's in 1948 and were bought by the Ashmolean Museum, Oxford. The site was investigated by Graham Webster in a series of archaeological excavations between 1959 and 1962, which revealed the full layout of the camp, except for areas destroyed by the quarrying. The Webster material is at Dorchester Museum and Art Gallery, but with some items on loan to Beaminster Museum. The permanent structure of the fort appears to have been built and occupied in the period 50–60 AD, and not started until after the abandonment of Hod Hill further east. The site was abandoned at the same time as the Boudiccan revolt (AD 61), and transport routes were already evolving along the Fosse Way axis to the North and the coast. The Roman road to Waddon followed an ancient trackway (the Wessex Ridgeway) that left the main Dorchester-Axminster road at Two Gates, passed through Eggardon Hill, then south of Beaminster, to enter Waddon from the east as it passed on just to the north of Lewesdon Hill, to the south of Pilsdon Pen, and the north of Lamberts Castle hill fort. In the 1950s tesserae were found in a nearby field to the north, which may be the site of the Fort's bathhouse, which would be one of the earliest mosaics in England. In 2023 Bournemouth University conducted new geophysics in the area, expected to be published in Brittania in November 2024.

• Lewesdon Hill
• Pilsdon Pen
• Hod Hill

• Dorset and the Second Legion, N.Field (1992), ISBN 1-871164-11-7

50°48′37″N 2°47′10″W / 50.81040°N 2.78625°W / 50.81040; -2.78625