[00:01.557]The mainland too, of course, had its burial chambers, like the long barrow at West Kennet.
[00:17.362]And there were also the great stone circles.
[00:20.270]The largest at Avebury，but the most spectacular of all at Stonehenge.
[00:35.820]By 1,000 BC, things were changing fast.
[00:39.551]All over the British landscape, a protracted struggle for good land was taking place.
[00:45.254]Forests were cleared so that Iron Age Britain was not, as was once romantically imagined.
[00:51.179]An unbroken forest kingdom stretching from Cornwall to Inverness.
[00:56.509]It was rather a patchwork of open fields, dotted here and there with woodland copses giving cover for game, especially wild pigs.
[01:07.621]And it was a crowded island.
[01:09.965]We now think that as many people lived on this land as during the reign of Elizabeth 2,500 years later.
[01:18.777]Some archaeologists believe that almost as much land was being farmed in the Iron Age as in 1914.
[01:31.421]So it comes no surprise to see one spectacular difference from the little world of Skara Brae, great windowless towers.
[01:40.845]They were built in the centuries before the Roman invasions.
[01:43.839]When population pressure was at its most intense and farmers had growing need of protection.
[01:50.630]First from the elements, but later from each other.