The Tour de Vésone is the most arresting Roman survival in Périgueux: a hollow cylinder of brick and stone, 24 metres high, that was once the inner sanctuary (cella) of a temple to Vesunna, the tutelary goddess of the Petrocorii. A long slot in one side marks where the wall was breached, probably when the building was robbed for fortification stone in the late Empire.
It sits in a small public garden a few minutes from the Vesunna museum, and the gap in the tower frames a clean line of sky from inside. There is no entry charge — you simply walk up.