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The Great Siege Tunnels

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  • Tours of Gibraltar Logo

As you circle down from the summit on the Gibraltar Rock tours, you come to the northern side of this solitary piece of limestone. On your way in from your Gibraltar transfers you might have seen a number of square holes dotted into the North Face of the Rock. These were formed during the Great Siege which lasted from 1779 to 1783, which now form an essential part of the Gibraltar rock tours.

The fact that the Great Siege Tunnels are placed in such a hidden corner of the Rock means that they are often less frequented by those on foot. With our Tours of Gibraltar you will get to see a magnificent human achievement, where the Royal Engineers managed to make headway through solid rock two and a half centuries ago. The intention was to cut off the Spanish advance as it had reached a point where cannons from Gibraltar batteries were no longer able to reach them as they were obstructed by the Rock.

Work on the tunnels was slow at first as workers mainly used sledgehammers and pickaxes to gnaw at the solid limestone, loosened by dynamite. The explosions were loud and created so much smoke and dust that a vertical shaft needed to be created as an air vent. Not only that, but finding the right amount of distance from the side of the rock proved tricky in an age where there was no such thing as computers and calculations were done very much through guesswork.

Eventually, work was completed for the first stretch of the Great Siege Tunnels in late 1783, although by then the siege had all but ended. At 908ft (277m) it included St. George’s Hall along with Windsor Gallery, King’s and Queen’s Lines as well as Cornwallis Chamber. Four cannons were placed in Windsor Gallery and others put at other points of the tunnel as can be seen in the Gibraltar private tours and Gibraltar semi-private tours. Curtains of ropes protected the gunners from the flashes and smoke, while a wet cloth made sure the rest of the gunpowder did not catch fire, causing a major explosion.

The tunnels were expanded in the 19th and 20th centuries when they were used for defence of the Rock during peace and wartime. Nowadays they are only visited by tourists who will be treated to Gibraltar attractions composed of light and sound that make it an exciting journey through time.