Landmarks: Australia

"Great" doesn't even begin to describe the immensity of this reef. The Great Barrier owns several "world's largest" titles, including: coral reef system, single structure made by living organisms, and natural phenomenon visible in space, to name a few. This is a SCUBA and snorkeling paradise, teeming with marine life of all shapes and sizes. The variety of animals — whales and porpoises, exotic fish and turtles, and colorful coral — is a huge tourist draw. About 2 million people visit the reef annually.
New life: The first reefs began sprouting on Earth about 5 million years ago; the Great Barrier Reef is only 500,000 years old.

This world landmark, completed in 1973, won architecture's highest honor, the Pritzker Prize, in 2003 for its distinctive 20th-century style. Architect Jorn Utzon, of Denmark, said it was "a symbol for not only a city, but for a whole country and continent." The structure's expressionist-modern design resembles seashells (intentionally), and houses the biggest and best of Australia's performing arts — Opera Australia, The Australian Ballet, the Sydney Theatre Company, and the Sydney Symphony. From above and from afar, the shells' roof shines a majestic white from the more than 1 million matted cream Swedish-made tiles, making this sight arresting in its detail and its grandeur.
Busy body: The Sydney Opera house hosts 3,000 events each calendar year.

Deep in the arid, dusty Outback in Australia's Northern Territory is a natural and cultural treasure. A geologic formation that towers above the vast red sandy plain, the monolith of domed sandstone is the backbone of a rich belief system of one of the oldest human societies on Earth, the Pitjantjatjara and Yankunytjatjara Aboriginal peoples. This UNESCO World Heritage Site is replete with springs, waterholes, and caves full of ancient paintings; it's a natural and spiritual capital dating back more than 10,000 years. Keep an eye peeled for some of the indigenous mammals to Australia like the wallaby, which is in abundance here. There are plenty of ways to enjoy the rock, including a traditional climb or helicopter tour.
Word to the wise: If you decide to make the climb, bring plenty of water - the temperature can rise to more than 100 degrees F even in the shade.