From the World Heritage inscription:
The Greater Blue Mountains Area consists of 1.03 million ha of sandstone plateaux, escarpments and gorges dominated by temperate eucalypt forest. The site, comprised of eight protected areas, is noted for its representation of the evolutionary adaptation and diversification of the eucalypts in post-Gondwana isolation on the Australian continent. Ninety-one eucalypt taxa occur within the Greater Blue Mountains Area which is also outstanding for its exceptional expression of the structural and ecological diversity of the eucalypts associated with its wide range of habitats. The site provides significant representation of Australia’s biodiversity with ten percent of the vascular flora as well as significant numbers of rare or threatened species, including endemic and evolutionary relict species, such as the Wollemi pine, which have persisted in highly-restricted microsites.
Katoomba and the Blue Mountains National Park is about an hour outside of Sydney. The amazing thing about Katoomba is that the town is located right on the rim of a canyon, which is one or the largest canyons in the world. You can literally walk through town and look out over the edge of the canyon.
The most prominent feature in Katoomba is the Three Sisters (shown above). In addition to the Three Sisters, you can take cable car rides to the bottom of the canyon where are the walking trails, several waterfalls, as well as hiking trails near the canyon rim.
The Blue Mountains is a must see for anyone visiting Sydney. You can easily take a train or drive to Katoomba from Sydney for a day trip.