Heinrich Nissen and the Orientation of the Templum

Of Heinrich Nissen, Clive Ruggles tells that he "deserves more than anyone else to be recognized as the earliest pioneer of modern archaeoastronomy". In fact, the German professor of ancient history studied the orientations of Egyptian and Greek temples and the orientations of churches too. However, Nissen is rarely mentioned in accounts of the early development of ideas and methods for archaeoastronomy. The aim of my contribution is to remedy the fact that Heinrich Nissen is not given due consideration and properly appreciated. I discuss in particular his Das Templum, where we can find his thought that the decumani of the towns were oriented to sunrise on the foundation day. He proposed to compare sunrise and decumanus azimuths to find this day. Moreover he linked it to Roman festivals. Some literature, where Nissen's thought has been discussed in the past, is also given.