WORK to conserve and stabilise the 4,400 year old Silbury Hill in Wiltshire began today.

English Heritage, working with specialist engineers Skanska, has exposed the door in the side of the Hill leading to the tunnel excavated by Professor Atkinson in 1968.

Working from a specially constructed platform built on the South West side of the Hill, the project team has cut away the turf surface of the Hill to a depth of some three metres, revealing the doorway used by the Professor and his team.

The works in the Atkinson tunnel are one of the three separate prongs of the conservation project.

Experts from English Heritage and Skanska will be re-entering the tunnel and excavating the forty-year-old backfill all the way to the centre of the Hill.

Using specialist mechanised equipment, as well as working by hand, the experts plan to re-use the steel supports inserted by Atkinson, while they take out the old, less stable backfill before painstakingly repacking every inch of the tunnel with chalk as they withdraw.

They will also be removing the support arches as they retreat, restoring the Hill to as near its original Neolithic condition as possible.

Dr Bob Bewley, English Heritage regional director for the South West said: "The engineering and archaeological works about to start here at Silbury Hill are the result of many years of meticulous research and planning.

"The Hill has been a stunning part of the Wiltshire landscape for 4,400 years and we hope that the work we do this summer will stabilise its structure and keep it safe for many years to come.

"It is a privilege for us to be able to get so close to the people that originally built the Hill, through the work we are doing over the coming months deep inside it."

The other two major components of the stabilisation work are the excavation and refilling of the crater on the top of the Hill, formed when the shaft sunk by the Duke of Northumberland in 1776 collapsed in 2000, and the filling of a number of craters and depressions on the side of the Hill.

English Heritage will be a launching a series of dedicated pages with regular project updates on its website at www.english-heritage.org.uk/silburyhill