This chapter deals with the genesis of architectural knowledge. In particular, it explores those rare moments when early modern English authors wrote about newly discovered examples of ancient architecture, the most important forms of architectural knowledge that existed. I will discuss three such accounts (all published in the Philosophical Transactions) of Roman York, Palmyra, and ancient Athens. These three texts share a preoccupation with truth and accuracy, as befitted the task of communicating highly sought-after architectural knowledge. They also demonstrate the degree of confidence of English writers in this period, not only in how they interpreted ancient architecture, but also in how they sought to criticize previous European authors on the subject. But most importantly, these texts reveal the extent of English intellectuals’ knowledge of the architectural principles of the ancient world and how that knowledge was in a state of flux.