This is the remains of an Iron Age hill fort. It is nice to wander around. There're 2 reconstructed houses but take their look with a pinch of salt. There is no information onsite except at the bathhouse and, at the start of the visit, general information on grain cultivation. That said, the pamphlet you get with your ticket has quite a lot of information.
Entrance is only €3. For €5 you get entrance to the Cultura Castreja museum in Briteiros and the Archaeological Museum at Guimarães. There are more items from this site at the latter (I went to the latter and it was quite disappointing though); the former has some items but also stuff about Martins Sarmento, who worked on this site. read more