We live in history, scurrying along streets with ancient names, past old buildings and historic landmarks, through protected landscapes, amidst plaques and statuary memorialising achievement and catastrophe. While the commemoration industry is focused on events that actually happened in the past – births, deaths, discoveries, battles, calamities – an important dimension of cultural memory concerns larger truths about origins and identities with a much looser connection to ‘the facts of history’. The central example in this paper is the complex medieval and post-medieval legacy of the opening of Geoffrey of Monmouth’s Historia regum Britanniae, which describes how Trojan refugees exterminated Albion’s indigenous giants and founded the British nation. How and why have material things (manuscript illuminations, printed books, turf-cut chalk drawings, elaborate costumes, immense figures in papier-mâché, oak, wicker, and even latex) preserved and embellished the memory of this foundation myth, alongside centuries of destruction, ridicule, indifference, and misunderstanding? Memory loss, confusion, and destruction are, it will be argued, essential pretexts for invention and survival, and underpin the dynamic interaction between material things, mythic history, and cultural memory.