Mammoth Cave, United States-Mammoth Cave National Park preserves the cave system and a part of the Green River valley and hilly country of south central Kentucky. This is the world's longest known cave system, with more than 400 miles explored.
by Ken Duncan photography - Known locally as ‘The Spa’, this delightful chamber in Western Australia´s Hamersley Gorge beckons the visitor Spring-fed, it is wonderfully cool, a refuge from the burning heat of the surrounding Pilbara.
29 Surreal Places In America You Need To Visit Before You Die
The ancient cave monastery of Vardzia in southern Georgia. The main period of construction was the second half of the twelfth century. The caves stretch along the cliff for some five hundred metres and in up to nineteen tiers. The Church of the Dormition,