Devizes is one of the best bases for exploring prehistoric Wiltshire. Avebury is just 8 miles north — the great stone circle and its surrounding henge are more atmospheric and far less crowded than Stonehenge, and you can walk among the stones freely. Stonehenge itself is about 20 miles southeast via the A360 and worth the trip for its iconic silhouette, though the visitor experience is more managed.
Closer to town, the Cherhill White Horse cut into the chalk escarpment north of the A4 is visible for miles and makes a good short walk. The Wandsdyke — a Dark Ages earthwork running east-west across the Wiltshire downs — can be walked in sections from several car parks south of Devizes. Marlborough, 12 miles northeast, has a wide high street and good independent shops, and makes a pleasant contrast to a morning of prehistoric monuments.