The ancient Nine Stones Circle (yes there are more than nine, and it is also known as the Nine Maidens*) on Belstone Common near Okehampton is quite easy to visit if you enjoy a short hike. Either walk up onto the Moor through the gate at the top of Belstone village opposite the water works (limited parking here) and follow the track towards Culliver steps for about a mile and you will find it on the shoulder of the hill overlooking the valley, or drive up onto the moor from Okehampton and take a longer walk down to Culliver Steps (you can park just off the military ring road) and walk up the hill to it. Ref: Sheet 191. 612 928

* More info can be found at this interesting website:
http://www.legendarydartmoor.co.uk/nine_maidens.htm