A short stay in Pamplona
Most of us know Pamplona for the annual Bull Run and it's several days party. It is also a staging post for the Camino de Santiago Frances.
Many of those who walk this route (100,000+ of them per year) begin in Pamplona to miss the tail end of the Pyrenees with a long climb followed by a sharp drop.
Pilgrims go through Pamplona and onto a town named Cizur Menor, where the route leaves the concrete streets to a hard surface, gravel road (no, it's not a trailGoogle car drove down it).
Personally I am not into religious pilgrimages. The one thing about them though is they are all over the world in various forms. Europe has many thousands of miles of them. Some have decent trails, others (like the Camino Frances) can be very boring, except for the people.
The Camino Frances is the last 500 of tens of thousands of miles of routes. It's kind of like a spider's web all over Europe, Eastern Europe and the Middle East. Two long sections are now broken (The Jerusalem Trail and the Templars Trail) because of the current wars in the Middle East.
If you come to Pamplona, you are going to run into the Pilgrims. They will stay at the same hostels as you. Chances are during the San Fermin, you won't see many because the prices go through the roof for the party. There are special hostels just for them (one night only, no lock ups but can be quite friendly).
There is a lot more information on the web about the road to Santiago.