or “Carmarthen Hills” or “Landsdowne Hills” like they were called in 19th century, are beautiful mountains situated in New South Wales, about 100 km from Sydney.  Formed around one million years ago as part of the Kosciusko Uplift during the Pliocene Epoch, they owe the name to the presence of oil bearing Eucalyptus trees, that fulfill the atmosphere with finely dispersed droplets of oil, which, in combination with dust particles and water vapour, scatter short-wave length rays of light, blue in colour.

The best moment to appreciate this particular phenomenon is at dusk when the atmosphere is the most dirty.

Althought sometimes the blue color pops up also during a day.

When in the 1850’s Gold was discovered in the Bathurst district, Blue Mountains became a new destination for a lot of travellers, and that would be the origin of the Blue Mountain railways, that are in use until today.

Situated on the pathway, little towns like Katoomba, Leura, or Blackheath still atract tourism but not that much the mountains itself.