Once upon a time you could roam freely across airports, but no longer. This final episode reveals how the easily accessible airport of late Sixties turned into one besieged by present-day security procedures and climate protesters. With rare archive and eyewitness accounts, it relates the events that have shaped our contemporary experience of airports - with their x-rays, pat downs and scanners. But although the airport's sheen may be tarnished, we're using them more than ever. Contributors including architect Lord Foster and author Will Self explore why.