This small island was the first National Wildlife Refuge ever created in the United States.

Fascinating military history, awe-inspiring wildlife encounters, and endless outdoor adventures draw people to this sprawling park.

This 19th-century building inadvertently preserved the handprints of its builders within its walls.

This site is where Lewis and Clark met and formed the Corp of Discovery with a few local men.

This monument is dedicated to Balto, the heroic Alaskan sled dog.

A park that allows you to get up close and personal with one of the world's largest open volcanic craters.

A resilient tree that has survived for more than 700 years in Guánica Dry Forest.

Rusting, graffiti-covered tanks litter the beach of this island, once used by the U.S. military for target practice.

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.

This bleach-white graveyard overlooking the ocean is accessed through a tunnel.

On this Puerto Rican island, many abandoned naval ammunition bunkers sit open while a few have been padlocked by locals as personal storage.

This niche museum devoted to ancient religious artifacts is shaped like the very thing it displays.

This rock in the middle of a river in Jayuya contains dozens of Pre-Columbian Taíno petroglyphs.

On a clear day, you can see all the way to the Virgin Islands from the top of this observation tower built in the 1960s.

Archaeological sites and great food inside the island's largest mangrove forest.

A park where people have been going to feed friendly pigeons since the 18th century

Former drug lord’s manor, now a theme park. Watch out for the hippos.

Thousands of pieces of art have been carved into the rock at the site of an ancient volcanic eruption.

An antique narrow gauge railway line still running through the Colorado and New Mexico mountains.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

The oldest continuously occupied public building in the United States.

Despite time, colonization, and the brutal New Mexican heat, these Pueblo ruins still stand.

Life-sized sculpture of a blue whale made of hand-recycled plastic trash.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.