The Solstices and the Orientation of the Roman Fort of Segontium

International audienceHere we discuss the orientation of Segontium, the Roman fort of Caernarfon, North Wales. As all the Roman military camps, this fort was planned according to an ideal pattern that was also applied to the coloniae, the outposts established in the territories conquered by Rome. The planning of military camps and colonies was based on a grid of parallel and perpendicular streets, where the main of them, the Decumanus, was specifically aligned. Some scholars are arguing that the Decumani were oriented according to the opportunity and environmental conditions of the place, some others are proposing the possibility of an astronomical orientation, to confer a symbolic meaning to the place too. Here we show that Segontium, besides having a very good defensive position and related orientation, had also astronomical alignments along the directions of sunrise/sunset on solstices. In fact, it had the same distinctive layout of another military camp of Roman Britannia, the Hardknott Fort, the orientation of which along sunrise/sunset on solstices we have already proposed