How was the Roman Empire invoked in Brexit Britain and in the United States during  Donald Trump’s presidency, and to what purpose? And why is it critical to answer these kinds of questions? explores how people’s perceptions and experiences of the ancient past shape political identities in the digital age. It examines the multiple ways in which politicians, parties, and private citizens mobilize aspects of the Iron Age, Roman, and Medieval past of Britain and Europe to include or exclude others based on culture, religion, class, race, and ethnicity.   The book uses quantitative and qualitative methods to investigate how premodern periods are leveraged to support or oppose populist-nationalist arguments as part of social media discussions concerning Brexit, the Italian Election of 2018, and the US-Mexican border debate in the United States. Analyzing millions of tweets and Facebook posts, comments, and replies, this book is the first to use big data to answer questions about public engagement with the past and identity politics. The findings and conclusions revise and reframe the meaning of populist nationalism today and help to build a shared basis for the democratic engagement of citizens in public life in the future. The book offers a fascinating and unmissable read for anyone interested in how the past and its contemporary legacy, or heritage, influence our political thinking and feeling in a time of hyper-connectivity.