Sightseeing sites in Gero

You can go see Gujo Hachiman, an old castle town. Or you can visit Takayama city which also has a lot of delicious things to eat and an old part of town which is interesting to walk through. You can also visit another onsen, Oku Hida Onsen.
https://planetyze.com/en/japan/gifu/gero-onsen/nearby