Archaeologists have pinpointed the construction of Stonehenge to 2300BC - a key step to discovering how and why the mysterious edifice was built.

The radiocarbon date is said to be the most accurate yet and means the ring's original bluestones were put up 300 years later than previously thought.

The dating is the major finding from an excavation inside the henge by Profs Tim Darvill and Geoff Wainwright.

The duo found evidence suggesting Stonehenge was a centre of healing.