This article showcases my recent research into the professional relationship between Christopher Wren and Robert Hooke, two of the early Royal Society's most prominent scientists and architects. There has been a recent tendency in architectural history to see Wren and Hooke as informal architectural collaborators, the co-designers of several important works in post-fire London. These include Greenwich Royal Observatory, the rebuilt parish churches in the City of London and, most prominently, the recently restored Monument to the Great Fire of London. In this article I argue that this reading of their relationship is a problematic one, ultimately dependent on an equally problematic account of their friendship. To do so I explore Wren and Hooke's professional relationship with regard to the Monument. I show, using new evidence, that their roles in the designing of the column have been misunderstood and that the final design can now be attributed to Hooke alone. Rather than being informal collaborators, Wren and Hooke did not stray from their duties as Royal Surveyor and City Surveyor, respectively, and Wren's contribution to the commissioning and designing of the Monument was as a consultant and ratifier only. In this respect their professional relationship as architects differed from their work as Royal Society scientists, in which informal collaboration was not only permissible but also encouraged. Overall, this conclusion has significant implications for our understanding of Wren and Hooke's careers as architects and sheds new light on one of early modern England's most important buildings.