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Hello, in many parts of the world, it's possible to see huge stones that have been placed

in the landscape, often their visual restriking and highly prominent.

They're called megaliths, and such stone monuments in Britain and Ireland most of the day from

the Neolithic period, the oldest ones are up to 6,000 years old.

In recent decades, scientific advances have enabled archaeologists to learn large amounts

about megalithic structures and the people who built them.

But much about these stones remains unknown and mysterious.

We need to discuss megaliths are Mickey Cummings, Professor of Neolithic Archaeology at the

University of Central Lancashire, Julian Thomas, Professor of Archaeology at the University

of Manchester, and Susan Greeney, lecturer in archaeology at the University of Exeter.

Susan Greeney, how do we define what a megalith is?

Well, the word megalith is formed two parts from the ancient Greek megal, huge and

lithus stone, so they're just large stones.

And the term gets applied to a whole range of different monuments, mostly in Europe,

dating from prehistory, but anything really that's been built out of very, very large

stones can be termed a megalith.

When you say most in Europe, we're implying that they're all around the world.

That's right, they're found in many different parts of the world, and although they're prehistoric

generally in Europe across the world, in fact in some places they're still being built

...