Unexplored UK: The Great Siege Tunnels – Gibraltar


The Great Siege Tunnels are the most famous tunnels carved into the rock of Gibraltar. They are argued to be the most impressive defence system built by man. Their origin began after Governor General Elliott offered a reward to whoever could work out how to get guns onto a projection of the northern face of the Rock, also known as The Notch. There was no option to build a path up to the Notch because it was on a vertical cliff face. Sergeant Major Ince suggested tunnelling and shortly afterwards permission was given; work began on 25th May 1782. They’re named after the Great Siege when during the American war of Independence France and Spain tried to take the rock from the British. The siege lasted from July 1779 to February 1783.


The tunnellers relied only on man power and gun powder. It look 18 men 5 weeks to tunnel an 8 feet square by 82 feet long tunnel. The original plan was to keep tunnelling straight to The Notch, however the fumes and blasts meant the miners needed air. A vent was opened to create air flow and 4 guns were mounted here as they realised it made a great embrasure. By the end of the siege in 1783 the tunnels were 277m long. After the ceasefire for the Great Siege, the French Commander Duç de Crillon visited the tunnels and is claimed to have said “these works are worthy of the Romans”, a quote that the people of Gibraltar are very proud of.

Work did not halt with the ceasefire in 1783. St George’s Hall, a chamber under the Notch, was created and 7 impressive guns were installed here. General Ince who came up with the idea of tunnelling was rewarded with a plot of land on the Rock and it is still named Ince’s Farm today.

The tunnels were reused during WWII but it is not known what for. The tunnels apparently housed a generator to power Gibraltar’s searchlights. We do know that the tunnels were extended but some of these have caved in and are not open to the public.


The Great Siege Tunnels are open from 9-18.15 daily with last entry being 17.45. We spent about an hour exploring the tunnels but longer could definitely be spent in here. There are toilets outside but no opportunity to purchase any food or drink so make sure your supply of water is adequate especially on a hot day.

There are five gun galleries to explore, all with a number of mounted guns to see. St George’s Hall is the largest and most impressive of these. The walk along the tunnels is at a constant slight downhill angle but this means the walk back is uphill. At the end of the tunnels there is a beautiful view over the sea to see the Notch that the British were so desperate to defend from the Spanish. Visiting the tunnels really shows the determination of the British to keep the Rock of Gibraltar. Hewing and blasting into the rock must have been utterly exhausting and the fumes made breathing difficult. Visiting the site and then trying to spot the tunnel’s openings in the rock face from the city itself put the soldiers’ determination into perspective.

Last Updated on 23 October 2023 by Michael

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