The Jenolan Caves, because they are located 164 kilometres from Sydney, are Australia's most accessible and popular limestone caves. They are deep in a valley on the far side of the Great Dividing Range and are 793 metres above sea level. Between Hartley and the Jenolan Caves, the road crosses the Great Dividing Range at an altitude of 1250 metres.The drive to the Caves includes one of the most dramatic and unusual stretches of road in New South Wales. After winding down a hill the road reaches a river with an incredibly blue pond and there, in front of the traveller, is the Grand Arch. Visitors have to drive into, and wind through, the main cave before emerging just below Caves House. The Grand Arch is the largest open cave in Australia. It is 24 metres high, 55 metres wide and 127 metres long. It is an extraordinary introduction to the whole experience of the Jenolan Caves.