Frederick II built the Lucera Castle in 1233 on the foundations of a cathedral, on a hill that was the highest point of the ancient Roman city. He used materials from remains of Roman buildings and built the original castle for use as an imperial palace. The castle is built around a square courtyard but on third level, the inside shape is octagonal, similar to Castel del Monte.
Charles I of Anjou added the extensive outer walls, 900 meters long with 13 additional towers, later in the 13th century to turn it into a military fortress. Today only remnants of the castle and walls remain but it is still an impressive sight and there are great views from the castle. You can also see the remains of the Roman Amphitheater on the other side of town and visit Alberto Longo Winery nearby.