In everyday language and in historiography, influential events are commonly described as “historic” but are rarely defined from a theoretical standpoint. Discussing temporal demarcations of events by scholars—in particular William H. Sewell Jr.'s foundational study of the Storming of the Bastille—this article considers the contemporary urge to define the event's temporal boundaries to better evaluate the alleged importance of certain events in history. Rather than perpetuating the constructivist idea that any event possesses a fundamentally interpretable character, it crafts a theoretical definition of the historic event that distinguishes between its flexible fringes and its rather stable core. Fixing an event as an anchor point on the timeline of history is thus presented as a process that provokes political, social, and—last but not least—financial controversies. As this article shows with examples from the history of revolutions reaching from the late eighteenth century to the early twenty-first century, such epoch-making events are essentially shaped by their flexible beginning and ending points. Although the cores of these events remain strikingly stable, their temporal fringes become objects of highly controversial discussions.