Sights to see in Ferrol?

If you walk down to the harbour from your hotel you can follow the Camino up into town passing various churches on the way, then to the big roundabout where the Camino turns right. (Note this and start from here again next day) Turn back into town to the main tourist office (sello) and walk along the pedestrianised main shopping area. Various interesting old buildings. If you want postage stamps the Correos is just off the pedestrianised zone and we bought stamps there for later postcards. We found this a good way to have a relaxed walk and view of Ferrol and also saved us walking down to the harbour and back on our first day as we were staying near the roundabout. Lots of little places to eat along the Camino route at the harbour and up through town. Eg both cafe and hostal Zara have good local food, one is near a little plaza, the other up near the tourist office.

To see an spectacular view of Ferrol I recommend to visit A hermida de Chamorro (Chamorro chapel). The best is to take a taxi about 8 euros. There is a romería (pilgrimage) once a year very popular in Ferrol. The chapel is usually closed.
Another point of interest it is San Felipe Castle defending the entrance of the ría (estuary) It is free (10h- 14h) (16h-20h) but it also requires to take a taxi about 10 euros

The oficina de turismo will tell you about everything of interest!

http://www.turgalicia.es/ficha-recurso?langId=en_US&cod_rec=1867&ctre=1000200

Click on "What to visit" for information before you go.