From the Wiltshire Times:

ENGLISH Heritage today announced the startling discovery of a Roman settlement around the base of Silbury Hill, part of the Avebury World Heritage Site in Wiltshire.

The 5,000-year old Hill is the largest man-made prehistoric monument in Europe, and its original purpose and use over the millennia since still mystifies archaeologists.

Today's revelation proves that a Roman community were living in the shadow of the Neolithic Hill, some 3,000 years after it was initially built.

The new data shows a village-sized settlement, equivalent in area to around 24 football pitches.

It straddled the Roman road from London to Bath, shadowed today by the A4, and lies where the main road crossed the Winterbourne River, an obvious stop-over point for travellers.

The research reveals that it was laid out in a typically Roman ladder settlement design, with buildings and small streets lying perpendicular to a central North-South thoroughfare.

The discovery was made using an array of highly sensitive caesium magnetometers, developed by the English Heritage Geophysical Team.

Using these sensors, the team can pick up localised anomalies in the earth's magnetic field caused by the influence of human activities, particularly the use of fire on naturally occurring iron oxides in the soil.

The magnetometers can sense soil disturbances up to 1.5 metres below the modern surface level and identify magnetic anomalies due to the most subtle features, such as an individual prehistoric timber post-setting.

Dr Neil Linford, English Heritage Geophysicist, said: "We are really excited by this discovery because we had no idea that a Roman village of such a size lay this close to Silbury Hill.

"Up until now, we have only been aware of some isolated Roman finds across the site, including what might be two wells, and the small Roman settlement on Waden Hill, 300 metres to the East of Silbury."

Dr Bob Bewley English Heritage Regional Director for the South West added: "To have found such a substantial and organised settlement is amazing. Without further investigation it is difficult to say, but it could be that what we have here is something like a roadside-village, where Roman travellers would have changed horses and stayed overnight on the way to Bath, but also a place of pilgrimage focused on the Hill."

... interesting; I've never heard the phrase 'ladder settlement' before ...