Two Roman Towns in Germany Having a Solstitial Orientation of Their Urban Planning

International audienceHere we discuss the orientation of the urban planning of two Roman towns in Germany, Kastell Kesselstadt and Mogontiacum, the Roman Mainz. As all the Roman military camps and coloniae, these towns were planned according to an ideal pattern, based on a grid of parallel and perpendicular streets. Using a software giving the sunrise azimuths on satellite maps, we show that Kastell Kesselstadt and Mogontiacum have the main axis of the grid oriented along the direction of the sunrise on the summer solstice, that is, that the towns have a solstitial orientation