The first excavation of Stonehenge in 44 years is currently underway and experts hope to solve mystery of why, when and how at least 80 stones were taken on a 250 km journey from the Preselis to the burial site, nearly 4,500 years ago.

This major research excavation investigating the bluestones of Stonehenge began yesterday, and will continue until April 11th.

The dig is being led by renowned academics Professor Geoffrey Wainwright and Professor Tim Darvill, who hope to date the arrival of the bluestones at the monument using advanced technology.

The project is the culmination of six years of research in the Preselis.

Bluestones, from the Carn Menyn region of the Preseli Hills, make up an integral part of the famous prehistoric monument.

Professor Wainwright said: "The excavation will date the arrival of the bluestones following their 250 mile journey from Preseli to Salisbury Plain, and contribute to our definition of the society which undertook such an ambitious project.

"We will be able to say not only why, but when the first stone monument was built."

Dr Simon Thurley, Chief Executive of English Heritage, added: "The bluestones hold the key to understanding the purpose and meaning of Stonehenge."

Daily video updates of the dig can be viewed at www.english-heritage.org.uk, and the excavation will be broadcast on BBC2 in the autumn.