The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

A six-ton, 12-foot-tall concrete prairie dog is touted as the largest in the world.

Literally a million fascinating cartographic artifacts are held in this sprawling university collection.

These molds for fiberglass statues have formed an eerie, accidental sculpture park.

This pseudo-steampunk weapons facility is the world's largest wood and glue structure, and packs quite a wallop.

A musical composition 1000 years in length plays at the Trinity Buoy Wharf in London.

Cold storage for agricultural biodiversity.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

A time-capsule monument reminding future generations of the importance of efficient and effective use of natural resources.

The ancient tomb acts as a calendar that keeps perfect time.

The largest earthwork effigy in the world.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

Natural catch-basin rocks covered in thousands of drawings spanning many millennia.

The clock that sets them all.

The longest living non-clonal organisms on Earth.

Step into the cool deep past and unknown future of who begat who.

Home to Hollywood history and a very special salt crystal.

Native Americans built this circle of stones, which was used to predict astronomical events.

The world's oldest individual clonal tree looks like a wimp despite standing tall for 9,550 years.

Sculpture garden of religious statues made it through Soviet rule.