In the desert of the South Australian outback, in one of Australia's hottest climates, is the town of Coober Pedy. In a bid to avoid the heat, much of it has been built underground. Visit underground houses, cafes and churches, and stay in underground hotels.

Coober Pedy is also known as the Opal Capital of the World, and there are plenty of opportunities to purchase the pretty gemstones – or even find your own.