Attracting legions of tourists every year, it is one of the world's most intriguing rock formations.
The Giant's Causeway, on the northern coast of Northern Ireland, was formed around 60million years ago.
But now, the volcanic formation is under threat - thanks to a scourge of tourists jamming coins between its stones, often for reasons of love or luck.
The National Trust, which cares for the feature, has issued a plea to visitors to stop the damaging trend, which is similar to the fixing of padlocks to monuments such as Paris's Pont des Arts bridge.
When the coins rust they expand to three times their original thickness and put 'huge pressure' on the surrounding rock, causing it to 'crumble', Trust expert Dr Cliff Henry said.
