This extraordinary underground passageway, 350m long, was built by the Knights Templar (a Christian military order) to connect their main fortress, just north of the black-and-white-striped lighthouse at old Akko's southwestern tip, with the marina (Khan Al Umdan). It was discovered by accident in 1994.

　　You can enter at either end; tickets to all the Crusaders sites are sold at both access points. Inside, buttons let you start films in either Hebrew or English.