Largest site of dinosaur footprints ever found includes more than 5,000 tracks.

Roman ruins top white travertine terraces formed by ancient hot springs.

Mysterious lost empire of the Silk Road.

Ancient paintings known as the "Sistine Chapel of Cave Art."

A hidden subterranean installation offers a view of the sky.

An Archaeological Wonder of Peru, and the largest stone ruin site in the New World.

White llama terraces dazzle in Peru's "other Machu Picchu."

Moonbows over Kentucky.

A hand-built folk art installation covered with messages of God's love.

Modern-day cave dwellers carve elaborate homes out of volcanic debris.

Ruins of a German Castle on top of a towering stone pillar.

Fossils, railroads, and waterfalls!

See the sky in a new way through this art installation.

A sacred lake composed of over 300 separate pools of highly concentrated minerals.

Every year, over 25,000 monarchs overwinter in Pacific Grove.

An intricate and amazing house built by architect Karl Junker.

Known as the most dangerous bridge in the world, the Hussaini Hanging Bridge is only one of many precarious rope bridges in Northern Pakistan.

Home to nearly a third of the world's mud volcanoes, Azerbaijan is home to a messy, bubbling, and sometimes explosive landscape.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

This extinct shield volcano is the lightning rod of the Cascades.

Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

A gargantuan crystal kingdom.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.