Leave London for an underground shell mystery in Margate

London’s trusty tube network shuffles us to work every day but, let’s get real, the Underground is pretty banal.

Margate’s Shell Grotto, around 80 miles south-east of the Central line, puts London’s subterranean spaces in the shade. The strange underground cave is unlike anything you’ve seen before and is something of a landmark on the Thanet coast.

Descending the chalk stairway, the first thing you’ll notice is the shiny walls. Very sci-fi. But lean in and you’ll see that this is no bygone ‘Doctor Who’ set.

The buried trail’s walls and roof are thickly covered with shells – around 4.6 million of them. Why?

The Shell Grotto was discovered in 1835, but its purpose and age are unknown. Theories range from cults to astrology to alien intervention, but no one actually knows its origin. It’s a real-life mystery. And if that’s not enough to intrigue you, who cares? It’s pretty.

Looking for more things to shell out on? Here are the best day trips from London. 

Fancy going a little further afield? Read our pick of the best weekends away in the UK.