Riversleigh, in the northwest of the state of Queensland, Australia is an area of around 100 square miles that's dotted with the fossils of mammals, birds, and reptiles. The entire area as well as some of Naracoorte is protected and has been declared a UNESCO World Heritage Site.
Naracoorte Caves National Park is completely on the other side of the country in South Australia. Naracoorte has 26 wineries that you can visit as well as campgrounds, a small cafe, and picnic areas. It's best to opt for a guided tour (they do them in several languages) where you can see the interior of the caves and, above all, thousands and thousands of bats.