The following links may be of interest:-
Dr Sandy Gerrard's site on roundhouses.
Alan Endacotts site, which gives information on the Sittaford Tor circle discovery and the Northern Moor.
Information on Stonehenge.
Dave Parks' excellent website, which provides more descriptions of the sites than I provide.
And his Dartmoor Cairns and Cists
The English Heritage PastScape database.
Devon Archaeological Society
The Devonshire Association
Plymouth and District Archaeological Society
Dartmoor National Park Authority
Dartmoor Walks Relics
The Megalithic Portal
The Dartmoor Archive
Divine Dartmoor Walks
The Dartmoor Resource
Dartmoor Walks Index
Liz Miall's walks