An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

Olfactory delights in San Francisco's Botanical Gardens.

Golden Gate Park's historic collection of plants.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Since 1973, this block has been home to the most concentrated collection of murals in San Francisco.

At the time of its completion, it was the tallest dam in the world.

The crumbling structure is a rare surviving relic of the area's bygone mining industry.

This rustic old building is said to be the most photographed barn in America.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

A beautiful geyser under environmental threat.

The first declared National Monument in the United States.

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

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

An experimental, automotive replica of Stonehenge.

This erect, phallic geological spire wasn't always named so domestically.

Otherworldly rock formations and ancient fossils abound in this unique stretch of Nebraska badlands.

Abandoned businesses, homes, and rusted cars are all that remains of this stopover town.

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

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

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

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

Every president in history is immortalized in bronze in downtown Rapid City.