I know of nothing in Pola, but down the road is the historic
Castro del Chao de San Martin, a prehistoric Celtic site with a museum that I found to be fascinating. You'd have to take a taxi there or ask about a local bus. This site is right along the Camino, farther on. We rushed to see it on our
day six, but it would have been more enjoyable of we'd had more time. In your bus/taxi ride you may see a preview of the Camino ahead!
I would also recommend
Lugo as a rest day if you have more time. It is a UNESCO site for its medieval walls. We reached Lugo on our
ninth day and spent two nights there. You can walk around the walls for another 2 km if you haven't had enough walking! But make it a stroll, as the views from the lofty heights, especially of the cathedral are wonderful and require frequent stops for grazing!
Happy planning and Buen Camino!