The Sanctuary of Panóias, also known as Fragas de Panóias, is located in Assento, União de Freguesias de Constantim/Vale de Nogueiras, Vila Real.

Built at the beginning of the 2nd to 3rd century by the Roman senator Gaius Calpurnius Rufinus, it was dedicated to the Infernal deities, headed by Serapis, and to the deities of the Lapitheans, an indigenous ethnic group of the region.

Based on studies of the monument, it can now be said that there was an initiation ritual at the site with a very precise order and itinerary: the murder of the victims, the blood sacrifice, the incineration of the victims, the consumption of meat, the revelation of the name of the highest authority in hell and, finally, the purification.