The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

The only quarter of the Old City not dedicated to a major world religion.

A "miracle" that seems to produce more holy fistfights than holy revelations.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

Perhaps the most spectacular grotto along the Algarve coastline.

Nine caves filled with recently-discovered archaeological finds under the houses and the streets of the most ancient district of an old town.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

Go inside to really appreciate this 500-year-old technological masterpiece.

Pilgrimage site for star-crossed lovers.

This elaborate temple was built around one of the Buddha's teeth.

This electric green sulphur lake in New Zealand looks like a cartoonish radioactive dump site.

Major tourist destination known for its bubbling mud-pools and hot thermal springs.

Handcrafted thermal spa washes away each night with the tide.

The world's only complete colossal squid specimen is on display at the Te Papa Museum.

The glacier tucked within a New Zealand rainforest.

Dolphins, ancient clams and hundreds of waterfalls make this one of the world's top tourist destinations.

Highly spherical boulders on the shores of New Zealand.

One of the world's steepest streets seems to have houses sliding down it.

A small, but award-winning beach known for its literally spotless reputation.

A cairn commemorating James Cook's second landing in Australia.

WWI hospital ship lost in a cyclone turns up on the coast of Fraser Island, where she remains rusted and forgotten.

The only pollutant in the clear blue water is sunscreen.

Come for the flowers, stay for the bats!

This historic national park is covered in the stunning ruins of red rock pueblos.