In the XI century the area of the Park becomes a northern barrier of the Norman Kingdom. Following this event, the Abruzzo becomes a fully integrated region in the political and economic affairs of the south. For defensive needs, the territory is characterized by the castling phenomenon that coagulate, i.e., of settlements scattered in fortified villages that are still the fundamental structure of the architectural and landscaping view of the Park. Systems of sight and communication, individual towers or walled, real fortifications allowed control over the territory and the dangers that could arise.
The castling and aggregation process of the population in the new centres is completed around the middle of the thirteenth century, coinciding with the reconstruction of the Celano Castle (destroyed by Frederick II in 1223) and the decadence of Alba. This last one had consequences of a certain importance on the organization of the territory: in fact it followed a deviation to the east of fundamental route Aterno Valley-Marsica (which since Roman period had his final part on St. Potito-St. Iona-Forme-Alba), and the consolidation of the new eastern route St. Potito-Celano, to the Tiburtina Valeria.