The discovery shows that its construction was a far greater collaborative effort than scientists believe.

Here's our science correspondent, Pallab Ghosh.

It's one of the most famous prehistoric monuments in the world and also one of the most mysterious.

Why was Stonehenge built in south-west England 5,000 years ago and what was it used for?

What we do know is that the giant altar stones are probably sourced locally from England.

The inner blue stones are from Wales.

And we now know that the central altar stone is from north-eastern Scotland and not from Wales as once thought.

The irony is that the discovery was made by a young Welshman.

He still remembers being brought to the site as a one-year-old in 1992.

I remember coming with my dad and being on his shoulders and looking over at the stones.

So it's nice to kind of come full circle and make this discovery at somewhere so special to me.

You're a proud Welshman and you've taken the Welsh status away from the stone.

So how do you think it'll go down in Wales?

I'm not sure they'll ever talk to me again.

It's a loss for Wales, no doubt.

But Wales has contributed so many rocks to this monument.

I'm sure Scotland can have one.

Anthony analysed the rock and discovered it had a unique date and composition.

In the journal Nature, he says it could only have come from the far north of Scotland, here in the Orcadian Basin, which includes Caithness, Orkney and Moray Firth.

So this is the altar stone, the heart of Stonehenge, now partially buried.

It's one of the largest stones here, at around six tonnes.

The big question is how on earth it was transported from north-east Scotland and why the people back then thought it was so important to bring it all this way.

They must have been very technically advanced to be able to do that, to bring it down by boat and bring it down on sledges or whatever.

And presumably it wasn't just a matter of engineering, there must have been some sort of social cohesion for the Scots and the Welsh and the English all to work together.

Absolutely, to bring this to here, a sort of focus in a way at that time, there must have been linking between all of these areas.

So what does this say about Neolithic society in Britain?

Well, it certainly implies great social connections and sophistication.

And I think what we've got to remember is these people were just like us in a way, you know, they were just as clever, but they had different technologies.

But to bring a stone of this size all the distance from what we now call Scotland is really quite something.

The new discovery has changed the story of Stonehenge and those that built it.

The tale is now of a people across Great Britain who were more interconnected and advanced than previously thought, who came together to build this incredible monument.

Pallab Ghosh, BBC News, Stonehenge.