A new online atlas has been launched capturing the location and key details of all the ancient hill forts in Britain and Ireland - including 30 in the Isle of Man.

Researchers based at the universities of Oxford, Edinburgh and University College Cork have been helped by citizen scientists from across the British Isles to collate the on-line database.

They discovered there are 4,147 hill forts in total, with Scotland alone boasting 1,694.

Mostly built during the Iron Age, the oldest hill forts date to circa 1000BC and the most recent to about 700AD.

The principal and highest hill fort in the island is the commanding and very exposed one on the summit of South Barrule, defended by two widely spaced ramparts.

The 30 Manx hill forts listed also include Cronk ny Merriu, a small coastal promontory fort just to the north of Port Grenhaugh. It includes the remains of a Viking longhouse.

And featured in the north of the island is Cronk Sumark, the dramatic Iron Age hill fort that rises above Sulby Claddaghs and which boasts impressive ramparts.

None of the Manx entries perhaps match Maiden Castle in Dorset, one of the largest and most complex Iron Age hill forts in Europe - the size of 50 football pitches, with huge multiple ramparts and a history of occupation from Neolithic times to the late Roman period.

Hill forts were central to ancient living for more than 1,500 years. They had numerous functions, some of which are yet to be fully uncovered, but clearly served as communal gathering spaces.

Fascinatingly, not all hill forts are on hills and nor are they all forts. Evidence shows many hill forts were first and foremost used as regional gathering points for trading and festivals, and some hill forts are located on low-lying land.

View the Atlas of Hill Forts of Britain and Ireland at https://hillforts.arch.ox.ac.uk