The so-called Iseum Campense, the impressive sanctuary for Isis and the Egyptian gods on the Campus Martius in Rome, is a monument central to various important debates. It was the largest temple for the Roman cults of Isis in the western Mediterranean and therefore it plays a central role in our reconstruction of the diffusion, appropriation, and character of Isis and the Egyptian gods in the Roman world. Moreover, the Iseum Campense mattered greatly to the Flavii as one of their main ingredients of self-definition and self-presentation. By making Isis and the Egyptian gods part of the imperial system, the Flavians even seem to have created a tradition that would strongly influence later (Roman) history, like Hadrian and his reign. From the Renaissance onwards the (site of the) Iseum Campense developed into an important and much-debated subject for the contemplation of Egyptian history and civilisation. In that respect it can be characterised as an important lieu de mémoire, in the sense that important parts of the mnemohistory of Egypt were shaped in Rome on the basis of the Iseum Campense and its finds. Athanasius Kircher is only one of many scholars that could be mentioned in this respect.