The Amazing World of War Machines S01 E04 Fortification - Bollards to Bunkers

Once man moved from hunter-gatherer to crop grower and farmer, he needed somewhere permanent to live, and to protect his property. From earliest civilization, forts, barricades and battlements were an intrinsic part of the world. Some of the oldest defensive structures still exist, and date back to the days of Assyria, Egypt and Greece.