Old medieval prison of Canet lo Roig Monument · Canet lo Roig, El Baix Maestrat, Castellón Image of Canet lo Roig, not of the place itself. Former jail or 'detainee depot' of medieval origin, from the 14th century, located on the steep Calle Planet d'en Roig. It preserves an ashlar stone doorway with a half-moon lintel leading to a chamber with a skylight and, from there, to two dungeons in total darkness. Photo: Columbusalbus (CC BY-SA 3.0) What to see and do in Canet lo Roig