The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Quite simply the largest tree in the world (by volume).

San Francisco's newly reopened hands-on science museum.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

A natural history wunderkammer in the middle of the desert.

The biggest solar telescope in the world helps reveal the secrets of our sun.

This iconic 1958 tower welcomes air travelers to Tucson with neon-lit letters and architectural style.

Religious statues built because of one man's bargain with God fill this peaceful sculpture garden.

This everlasting lightning storm may be the world's largest generator of ozone.

The design of the Palacio Salvo has been described as "a lighthouse on top of a building."

This 16th-century monastery was founded to cloister the daughters of wealthy local families.

With nearly double the depth of the Grand Canyon, this Peruvian canyon is one of the deepest in the world.

These ruined Incan mausoleum towers still bear carvings of sacred animals on their blocks.

The Uros people live on floating reed islands in lake Titicaca.

Built on the remains of one the Incas’ most important gathering spots, this square keeps the spirit of a fallen empire alive.

An Inca spa, military outpost or maybe… both?

Situated on a sacred Inca site, this 16th-century cathedral took nearly 100 years to build.

Haunted by its violent past, this colonial bastion was the largest Spanish military installation in the Americas.

A monument to the conquistador became increasingly controversial in the very city that he founded.

An elaborate shrine dedicated to the four corners of the world unfortunately misses its mark.