What was it Horace said about journeys? You change the sea you change the sky but you cannot escape the inside of your head. The same is true of travellers to the past. Charlotte Higgins’ motive in this discursive travelogue is to explore our relationship through the centuries with Roman Britain and the variously coloured filters through which we have viewed it. When Mortimer Wheeler excavated Maiden Castle in 1936, he was fraught with memories of Passchendaele in 1917 and by the recent death of his wife. Accordingly he found a “war cemetery” – the twisted corpses, as he thought, of Britons caught in Vespasian’s westward onslaught in the AD 40s. These were relics “eloquent of high tragedy”, he wrote. Modern archaeologists, however, find no eviden