A hundred years ago, the labyrinth of spectacular caves beneath Dan-yr-Ogof in the Swansea Valley lay undiscovered.
Today, exactly a century after they were discovered on August 21, 1912, they are known as the National Showcaves Centre For Wales and are are among Wales’ best known visitor attractions welcoming over 70,000 tourists a year.
Set in the stunning Brecon Beacons National Park, in 2005 the caves won a TV search for “Britain’s finest natural wonder” beating off competition from the likes of the Cheddar Gorge and even the iconic White Cliffs of Dover.
The caves have hosted music concerts and weddings and were used during World War 11 to hide art treasures in the event of a Nazi invasion.
And the attraction now also boasts one of the biggest full-scale model dinosaur parks in the world as well as a replica iron age hill farm, a Victorian farm, a museum, a collection of working shire horses and a millennium stone circle.
The discovery of the caves was down to present day owner Ashford Price’s heroic relatives, local farming brothers Tommy and Jeff Morgan, who were the first to discover the caves in modern times on August 21, 1912.
It was the year of the Titanic disaster and of the ill fated Scott expedition, a time when movies were still silent and cars were rare.
The Morgan brothers were not initially looking for a vast cave system but were trying to find the source of water which was constantly pouring out from a cave entrance on their farm at Dan yr Ogof in the Upper Swansea Valley.
Not knowing what they would find underground, the intrepid brothers armed themselves with a revolver and took along ropes, candles and supplies of food.
The brothers’ initial expedition was halted by a large lake so, using arrows marked in sand and earth to find their way back, they returned to the surface to get a coracle in which they crossed the “underground sea”.
The pair discovered a wonderland of spectacular underground stalactites and stalagmites which dated back to the time of the dinosaurs.
They eventually crossed three more lakes in the same manner, but were stopped by a tight crawl.
Once the caves had been discovered the Morgan farmers took tourists on trips into the caves using candles to light their way.
Mr Price said: “Tourists in the early days of the attraction were expected to wade and swim through icy cold water, to climb underground cliffs and negotiate huge boulders covered in slimy mud.”
A hundred years on the caves are still run by descendants of the original cave explorers and since the original discovery in 1912 more than eleven miles of caves have been discovered by caving experts using updated equipment.
As well as their current role as a tourist attraction, the caves also doubled as an arms and art store during World War II
The ammunition was intended to be used in the event of a Nazi invasion and the underground storage of priceless paintings and other artworks was intended to keep them out of the hands of any German invaders.
Water from the caves was also piped down to Swansea when the water mains were damaged by bombs during the infamous three-night blitz on the city.
In older times, the long usage of the caves dating back 3,000 years has been shown by the discovery of 42 human skeletons dating back over 3,000 years to the Bronze Age.
Items such as bone pins, pottery, coins, iron, bronze and silver rings have also been found in the cave, as well as relics dating to the time when Roman legions were stationed in the area.
In one of the most unusual ceremonies ever performed, the bones were returned underground and reburied in the Bone Cave.
Mr Price added: “To mark our 100th year the caves have installed a new hydro plant costing over £300,000.
“This plant makes the caves the first ‘self sufficient’ energy producing attraction in Britain.
“We have also installed an ‘electrical hook-up point’ to recharge electric cars.
“This is the first time a hydro plant has been used to provide the power to recharge electric vehicles.
“Finally, we have recently been planting over 80,000 broad leafed trees on the mountains surrounding the showcaves to record our 100th birthday.”
In 2005, a competition run by TV channel Five asked readers of the Radio Times magazine to vote for their "finest natural wonder".
They chose the National Showcaves of Wales ahead of attractions including Giant's Causeway, the White Cliffs of Dover and Cheddar Gorge.
In 1953 members of the South Wales Caving Club blasted a way through boulders to discover the Cathedral Cave, decorated with thousands of delicate cave formations.
Modern lighting and dramatic music now bring the huge cave to life and it has been the venue for subterranean concerts and even weddings.
The caves at Dan-yr-Ogof are made of carboniferous limestone, formed some 315 million years ago.