In the centre of Vietnam lies Phong Nha-Ke Bang National Park, home to the oldest limestone caves in Asia and evidence of the ancient civilisations who sheltered in them.
Covering 2,000 km² – an area twice the size of Hong Kong – the park is part of one of the world’s two largest limestone regions, made up of hundreds of caverns created by underground rivers.
This unusual karst landscape boasts beautiful limestone formations created over the last 400 million years.
Phong Nha-Ke Bang is considered the oldest and most distinctive example of karst in Asia, earning it the title of UNESCO World Heritage Site.
Perhaps the most incredible formation in Phong Nha-Ke Bang is its largest cave, Han Son Doong, meaning Mountain River Cave.
Measuring 150 metres long and 200 metres high, the ceiling reaches twice the height of Big Ben.
What makes the caves of Phong Nha-Ke Bang so impressive are the huge stalagmites that grow from the floors and stalactites that hang from the roofs, earning the park its name which means ‘cave of teeth’.
Stalagmites and stalactites are formed by water dripping from the ceiling of a cave, gradually depositing minerals that build up from the floor or down from the roof in needle-like formations.
Of the park’s 300 caves and grottoes only a few are accessible to people, but evidence has been uncovered to show that the caves have been used by humans for thousands of years.
Archaeologists have found hieroglyphs and altars in some of the caves attributed to the Champa people in the 9th and 10th centuries who controlled southern and central Vietnam.
Even earlier evidence of human occupation are Neolithic axe heads found in some of the caves, dating back up to four thousand years.
More recently, the caves of Phong Nha-Ke Bang were used by the North Vietnamese during the Vietnam War as a hospital and ammunition depot; artillery scars can still be seen on the outside walls of some of the caves.