Assergi is a small stone village below the southern side of Gran Sasso, close to the road and cable-car access for Campo Imperatore. It is often passed through quickly, but it makes a useful low-key stop before or after the mountain.
The village gives some human scale to the massif: narrow streets, mountain light, and a sense of how Abruzzo settlements sit tucked under much larger geology. Stop for a short wander rather than a full sightseeing programme.