Segontium and Caernarfon's uncertain Roman continuity

Segontium stood on the hill above the later castle and town. Caernarfon's Welsh name is connected with a stronghold in the land opposite Môn, the Welsh name for Anglesey. What happened to the fort and its civilian settlement after the Romans left Britain is uncertain. One possibility is that the fort was abandoned and its materials taken for nearby buildings. Another is that the civilian population moved inside the fort for protection and the later settlement developed from there. A settlement existed before Edward I began building, although the precise continuity from the Roman period is unresolved.