The article draws together studies on encyclopaedic expressions throughout history with Foucault's notion of heterotopia, i.e. actually existing utopias or ‘other’, particular spaces that exist besides society's regular spaces and which work according to their own rules. It explores how we can understand contemporary online encyclopaedias, specifically Wikipedia, as digital heterotopias. For this it investigates Wikipedia as an archive for our cultural memory in its different – and sometimes contested – versions. In conclusion, participatory online encyclopaedias are framed as a continuation of an Enlightenment ideal as well as distinct networked spaces that are made possible through the affordances of the Internet.