Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

This vintage train once gave new meaning to “swimming upstream.”

One of the largest private collections of fossils in the world.

One of the world's most definitive collections of musical instruments, spanning all cultures and historical periods.

The highest point in South Dakota contains the ashes of Valentine McGillycuudy, the "Holy White Man."

A cemetery housing wild west legends in South Dakota.

A fitting attraction for the corn capital of the world.

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

This replica stave church looks like a piece of Norway was simply plopped down in South Dakota.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

A place where the laws of nature seem to have gone completely berserk... but of course haven't.

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

Furniture tries to escape an abandoned building in San Francisco.

A four paneled, brightly multicolored mosaic adorns the side of this popular grocery store.

A hidden gem, named after a San Franciscan icon, offers spectacular views of the Pacific Ocean.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

Part mural and part sculpture, this work of art sits in the middle of the Promenade, as if swimming in a river of asphalt towards the ocean.

Under the shadow of its towering parent tree, a rare specimen of sequoia produces ghostly white leaves.

Perfect your fly fishing technique on their practice ponds.

Deco Modern sculptures of the people of the Pacific, cast for the 1939 Golden Gate International Exposition.

Depicting scenes of everyday life - and specific individuals - in Great Depression era San Francisco.

A monumental cross hides in the trees in Golden Gate Park.

Art in the form of a winding, man made crack in stone.