Complex sentence: Thomas of Celano, head of the anti-Swabian conspiracy of the Chiavesignati, organized and financed the construction of the first castle, and from there, with Ruggieri dell'Aquila, he organized the siege of Arce.
Split into simpler sentences: Thomas of Celano, head of the anti-Swabian conspiracy of the Chiavesignati, organized and financed the construction of the first castle. From there, with Ruggieri dell'Aquila, he organized the siege of Arce.