During the second half of the 12th century the members of the Templar Order began building their quarter in the south-western part of Acre.
A writer who lived in the city at the end of the 13th century describes their fortress as follows: “The Templar Fortress was the strongest one in the city and, in the main, abutted the sea line. Its entrance was protected by two strong towers with walls 28 feet thick. On either side of the towers two smaller towers were built and each tower was topped by a gilded lion.”
A tunnel led eastward from the fortress, the remains of which are now covered by the sea. The lower part of the tunnel was carved from natural stone, and its upper part was built from hewn stones covered by a semi-barreled dome.
The tunnel transverses the Pisan Quarter and leads to the city port in the east, a distance of 350 meters. The tunnel was discovered in 1994 and was opened to the public in September 1999. In order to open it to the public it was necessary to clear away dirt, to install a system of pumps in order to maintain a fixed groundwater level and to build a wooden path and install lighting.