The period of Norman domination, and, above all, the Swabian period under the guide of Federico II, led to a reinforcement of the role of the cities and contemporarily to the development of the inland areas. At the same time, the structuring of the military and defensive system, important for the quality and quantity of evidence that has reached us, considered the castles – usually located on the highest point of the city, or on the high grounds that dominate the territory, or on the sea – to be the cornerstones of its organisation. Splendid examples are the castles of Barletta and Trani, the castle of Minervino and Canosa, and the interior of the citadel of Garagnone, besides, naturally, the cited Castel del Monte, which despite its symbolic and astrological implications, had a strategic position in that it dominated an extremely vast territory.
In addition to the large fortifications, which are monuments to laic and military power, the most exciting image of these cities can be found among some of the most beautiful cathedrals of Puglia, and among the most beautiful examples of the Puglian-Romanesque style. All built between the 11th and 13th centuries, mainly in local stone, with complex and very fine decorations (especially around the portals, in the door-posts, in the rose-windows and in the jutting trusses) which contrast the sobriety of the bare walls, they are generally oriented, and often connected, with other important monuments of a religious nature. Most of these churches have older crypts under them, which are also of extreme architectural and historical value.