The Southern Highlands sit about 110km south west of Sydney on the Great Dividing Range, which is less a genuine mountain range than just a series of heavily eroded uplands. The altitude varies along the range. Katoomba in the Blue Mountains, about 100 km west-north-west from Sydney, for example, has an altitude of 1,017m (call it 3,340 feet), while 3 of the principal towns in the Southern Highlands have altitudes of 635m (Mittagong), 690m (Bowral), 678m (Moss Vale) and so on. It's an elevated stretch of land relative to many of the areas around it which gives it a cool, temperate climate for much of the year (for what that's worth in an Australian summer), but it's hardly "in the mountains". It has a population of around 48K people.
It tends to be a pretty traditional part of the country, and I mean that in a good way. It attracted quite a few people of Scottish descent in years past, probably because of the name. However any Scotsman who went there for the geography would be sorely disappointed. It's much warmer and drier than Scotland (but that's a low bar) with the added risk of bushfires (but hey, welcome to Australia). Regardless, there is a major Scottish festival every year in the Southern Highlands. And hopefully there always will be.
It's a place for getaways if you prefer trees to the ocean, a place to go antique hunting, a place to relax and enjoy good food and wine.
To the extent that I documented it previously in these galleries it was as part of the road to Canberra. However since the Southern Highlands sits directly to the west of the lower part of the Illawarra (where I am now based), I'll be visiting it more often and it deserves its own gallery.