The Arsenal is the most striking structure among the ones in Trabzon. According to the Yıldız Palace records, it was constructed in 1305 in Islamic Calendar (1887 in Gregorian calendar). Both the inscription and the signature of Sultan Abdülhamit II over its door confirms this date.

The Arsenal, with a 25-40 m diameter, includes two circular structures; one inside of the other. The inside one is four storied whereas the outer is three storied. Both structures include 3 windows with oval arches. A high protective wall surrounds the Arsenal. On the west side is a guard house. During the Russian occupation between 1916 and 1918, the Arsenal served as an ammunition dump, and its roof was demolished by an explosion on July 9, 1919.