Tour de Grisset
Fréteval, France
The Tour de Grisset (Grisset Tower) is the remains of a small, Gallo-Roman temple or fanum located in Fréteval, Loir-et-Cher, France. It is one of the few Gallo-Roman fana to still be standing, and perhaps the only one with its brick vault still in place. Excavations in the 1960s revealed a bath complex and series of other structures at the site, and it has been proposed that a small, secondary agglomeration of structures (possibly additional fana) may also exist there.
Archaeological site data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).