This article explores how we can understand contemporary participatory online encyclopaedic expressions, particularly Wikipedia, in their traditional role as continuation of the Enlightenment ideal, as well as in the distinctly different space of the Internet. Firstly we position these encyclopaedias in a historical tradition. Secondly, we assign them a place in contemporary digital networks which marks them out as sites in which Enlightenment ideals of universal knowledge take on a new shape. We argue that the Foucauldian concept of heterotopia, that is special spaces which exist within society, transferred online, can serve to understand Wikipedia and similar participatory online encyclopaedias in their role as unique spaces for the construction of knowledge, memory and culture in late modern society.