original: Construction was completed in 1254 under Frederick's son, Conrad IV of Germany.
simplifications: Building was done in 1254 under Conrad IV of Germany. Construction was finished in 1254 by Frederick's son, Conrad IV of Germany. Frederick's son Conrad, IV oversaw construction in 1254. Construction was completed in 1254. Conrad IV of Germany was the ruler. He was Frederick's son. It was finished in 1254 under Frederick's son, Conrad IV of Germany. Construction was done in 1254 under Frederick's son. He was Conrad IV of Germany. Construction was finished in 1254 under Conrad IV of Germany. In 1254, construction was completed under Conrad IV of Germany. Building was done in 1254 under Frederick's son, Conrad IV of Germany. Construction under Frederick's son Conrad IV of Germany was completed in 1254.