Know Before You Go
To find Puig Castellar ("Putch Castel-YAR"), take the metro to Singuerlín or Can Zam. There are several routes you can take, each taking around an hour to ascend. There are some signs leading to Poblat Ibèric, but it helps to have a map or smartphone.
There's a clearing with some informational signs, and the village itself is a couple minutes' walk up the hill from there.
Mobile phone service is good throughout the route. On the western route there is a restaurant but otherwise no amenities, so bring enough water and snacks for three hours of activity. You may meet the occasional locals on the routes but the area is generally very tranquil.