[00:03.076]Many of those towers still survive, though none are as daunting as the great stone stockade on Arran, off Ireland's west coast.
[00:16.481]And they didn't just spring up around the edges of the British islands， all over the mainland, too.
[00:23.079]The great hill forts of the Iron Age remain visible in terraced contours at places like Danebury and Maiden Castle.
[00:30.248]Lofty seats of power for the tribal chiefs, they were defended by rings of earthworks, timber palisades and ramparts.
[00:46.029]Behind those daunting walls, this was not a world in panicky retreat.
[00:55.084]The Iron Age Britain into which the Romans eventually crashed with such alarming force was a dynamic, expanding society.
[01:04.099]From their workshops came the spectacular metalwork with which the elite decorated their bodies.
[01:10.087]Armlets, pins and brooches and ornamental shields like this, the so-called Battersea Shield.
[01:37.484]Or the astonishing stylised bronze horses, endearingly melancholy in expression, like so many Eeyores resigned to a bad day in battle.