The Great Siege Tunnels in Gibraltar, Gibraltar

The Great Siege Tunnels is one of the greatest historical attractions in Gibraltar. The Siege Tunnels were carved out by the Merchant Marine to defend Gibraltar from the mainland during the Great Siege of 1779 to 1783. The original goal of the tunnels was to get a cannon on the northern face of the rock known as the Notch. Originally the tunnel was only 82 feet in length, but by the end of World War II, the tunnels had reach a winding distance of over 30 miles.

Holes for cannons are carved into the rock all along its mainland-facing side. As you cross into Gibraltar, look closely and you should be able to spot these holes in the rock face. (A wet cloth was hung from the rod above the cannon to prevent sparks flying back and igniting the powder.)

The Moorish Castle, St Michael's cave.