While there is no definitive evidence that Frederick II used Castel del Monte for astronomy, the unique architectural features, such as the precise orientation and alignment of the castle, suggest an interest in stargazing and using the sun as a natural clock. Some theories suggest that the octagonal design and placement of towers may have had symbolic or practical significance related to celestial observations, possibly influenced by Frederick's interest in science. However, the exact purpose remains uncertain, and it is debated among historians.