The entrance to Ingleborough Cave in Clapdale near the village of Clapham in the Yorkshire Dales, North Yorkshire.
The cave entrance had been visible for centuries, but in 1837 Reginald Farrer’s workmen broke away a huge stalagmite barrier to release the waters of an underground lake and open up the cave. Now visitors can make a 1 km journey through one of the best show-caves in the UK, passing some amazing limestone formations with stalactites and stalagmites up to 350 million years old. Admission charge.