The name Kakadu, in fact, is derived from the word "Gagudju." The Gagudju, who occupied the Kakadu area for thousands of years, left behind a priceless legacy: thousands of ancient rock paintings. These paintings, most of which are found in caves and overhangs along the cliff known as the Arnhem Land Escarpment, are among the oldest in the world: some date back at least 20,000 years. Among them are colorful images of kangaroos, buffalo, fish, and thylacine, a Tasmanian tiger that was extinct 5,000 years before Europeans arrived in Australia.

These include the evil spirit Nabulwinjbulwinj, who killed women by hitting them with yams and then devoured them, and Namarrogon, the lightning man. The Gagudju believed that the paintings kept alive the Dreamtime, an ancient concept of harmony between man and the environment. A few Gagudju still live in the park, but the last rock paintings were made about 20 years ago. Today, they practice their art on pieces of bark rather than rock walls.

In recognition of its rich stores of wildlife and art, in 1981 Kakadu was named a United Nations World Heritage Site, placing it in the company of the Great Wall of China, Stonehenge, Westminster Abbey, and other areas of "outstanding universal value."