More information: http://en.wikipedia.org/wiki/Six_Hills
The Six Hills are a collection of Roman barrows situated alongside the old Great North Road in Stevenage, Hertfordshire. They form the most complete Roman barrow group in the country. For almost two thousand years, travellers along the Roman road that eventually became the Great North Road have passed these six large mounds. Their origin and purpose has been the subject of much speculation! There are also ancient and unusual species of grass found on and around these hills, which pose further interest.