On the camino I became a real fan of Romanesque art.
At least take a peak at any church that is open. I'll name a few favorites as I go along.
Poke around in Roncevalles.
In Pamplona we saw the cathedral for free by going to mass (we entered the city as the bells were ringing.)
We did not see the attached museum. The Museum of Navarra was nice but we saw it post-camino and had plenty of time. It is close to the camino. Bring your credential as I remember it is good for reduced admission.
Be sure to see the church in Navarette; high ceilings and a huge retablo of gold. The Monasterio de Santa María la Real in Nájera is recommended. We missed the cathedral in Santo Domingo and I regret it.
In Burgos see the Burgos Cathedral and museum. I think we spent 3 to 4 hours here. I already mentioned the Museum of Human Evolution. Of historical interest is the fort on the hill to the north of the cathedral (Napleonic War). We climbed the hill for the view but passed on the fort visit.
I loved the Romanesque church (museum) in Fromista. It is right on the camino.
There is a Romanesque church in Carrion de Conde that was destroyed but revitalised as a museum. Not terrific but well worth some time and the cheap admission. As in all the museums and churches that I remember any explanatory signage was just in Spanish. Fortunately I could usually figure out half.
There are a good number of churches to see in Sahagun. A special note about the Senora la Peregrina though. You can get a compostella here (when the museum is open) that indicates you have reached the halfway point on the
Camino Frances. But pass on the museum. We liked a rural Spain to 1950 photography special exhibit most of all.
In Leon there is the gothic cathedral of course but during the camino I found a great appreciation for the romanesque period. The camino in Leon passes the Basilica of San Isidoro and attached to that is a museum that conatains books and other objects of that period but there were two things that absolutely fascinated me, the 11th century Royal Pantheon and the chalice of Dona Urraca, one of the Holy Grails that Europe is so full of. The Royal Pantheon is sometimes called the "Sistine Chapel of Romanesque art" and a recent book documented the chalice (and did such a job that it might be off display for awhile.) If you are a Gaudi fan then see the Casa de los Botines (in front there is a statue of Gaudi sketching the building.) It won't take long to see this so don't fret about putting it into an already tight schedule.
Stop to look at the modern church at La Virgen del Camino. It's a change of pace.
We had a long recovery layover in Astorga and so we got to see these:
The cathedral and attached museum
Still lots of defensive walls
An outdoor exhibit of Roman floor tile mosaics
Your friend is going to want to see the Roman Museum. The grave stones impressed me the most.
The Chocolate Museum was fun.
The Episcopal Palace, an early Gaudi work. Peg loves Gaudi. We stopped in Barcelona for him first.
Peg really liked the castle in Ponferrada. Later, from near the post office, you can catch a bus most of the way to Camponaraya to make up the time spent there and avoid a long walk on pavement (pavement pained Peg).
Physically attached to the cathedral in Santiago is the Church of Santa María a Antiga da Corticela that dates to the 9th century. It has a few minimalist modern touches that go well with it.
I wish that we had gone to Eunate and Samos.
https://en.wikipedia.org/wiki/Pamplona_Cathedral
https://es.wikipedia.org/wiki/Museo_de_Navarra
http://www.navarra.es/home_en/Temas...cciones+permanentes/Museo+Navarra/Default.htm
https://en.wikipedia.org/wiki/Santa_María_la_Real_of_Nájera
https://en.wikipedia.org/wiki/Museum_of_Human_Evolution
https://en.wikipedia.org/wiki/Chalice_of_Doña_Urraca
https://en.wikipedia.org/wiki/Basilica_of_San_Isidoro
http://www.santogrialdeleon.org/en/basilica-of-san-isidoro/royal-pantheon
http://www.santogrialdeleon.org/en/
https://en.wikipedia.org/wiki/Casa_de_los_Botines
https://en.wikipedia.org/wiki/Astorga,_Spain
https://en.wikipedia.org/wiki/Astorga_Cathedral
https://en.wikipedia.org/wiki/Episcopal_Palace_(Astorga)
http://www.ayuntamientodeastorga.com/quevisitar/museos.htm