Spain recommendations for a post bar exam trip?

I’m planning a post bar exam trip with a leg in Spain in late August of this year and I’m curious where people recommend. I have around 2 weeks before I am meeting up with friends elsewhere on the continent. I’m looking for something that has cool architecture and history, but ideally not swarmed with tourists. I’m gonna be there solo, so places people have been to alone or with cool hostels would be welcome. 🙏