The Knights Tunnel is located in the city of Acre, and its length is about 350 meters. It was previously used as an underground passage that connected the castle and the port. The lower part of the tunnel is carved into the rock, and the upper part of the tunnel is built of polished stones with a cylindrical arched dome. It was also a temple for the Knights Templar, a military group of monks that was working to guard pilgrims who came from Europe to Palestine in order to visit the holy sites.