The bird was flying at around 2500 m. It was circling among a group but was noticeably larger than the others. Bearded vultures can have a wingspan of 2.6 - 2.9 m, so they're pretty huge. They feed almost entirely on bone marrow. They have been observed flying high with a large bone and dropping it to fracture it into smaller chunks.
I waited for a while for it to return, but something else turned up:
I guess this one is a golden eagle
Later on, I saw another unknown bird of prey chasing a raven:
Possibly a juvenile golden eagle. Young bearded vultures have dark heads, so it's not one of those.