The Stonehenge Enigma

Stonehenge is one of the world's greatest mysteries. Now, a new discovery found deep in the soil of the surrounding area is threatening to upturn everything we think we know about this 4,500 year-old landmark. Rob Bell joins archaeologists, scientists and engineers who have uncovered a vast, previously undetected monument that is many times the size of the original henge.

• Kate DooleyDirector

• Rob BellPresenter