Craggy concrete faces are hidden in the walls of this artificial cave along the San Antonio River.

Three hundred years of preserved Spanish colonial history in San Antonio.

A National Historic Landmark with a scenic clock tower and park filled with deer and peacocks, plus a military museum.

A tall smoke stack and boarded-up buildings are all that's left of the pioneering plant.

These boots are made for selfies.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

Mountain known by the Tillamook Tribe as "the place of the supreme deity."

No one knows how this Pacific Northwest spruce tree came to have so many trunks.

Train debris from the deadliest avalanche in United States history can still be found in the ravine where so many perished.

Fossils, railroads, and waterfalls!

A surreal landscape where fanged rocks rise from the ground and the ocean feels like a great mystery.

One man's eclectic collection of treasures found at sea.

This dilapidated ship carcass covered in trees is a striking sight.

Hundreds of hopeful gold miners came here to get rich, but only two years later the small town was deserted.

The illuminated falls are a gem in North Cascades National Park.

This sci-fi gazebo located in a Washington power town is made from old bits of industrial electrical equipment.

Touch an actual dinosaur bone at this eclectic trove of Rocky Mountain treasures.

A chance to sleep among the firs and pines of the Oregon forest.

Romans built the world's tallest artificial waterfall in 271 BC.

This isolated structure beckons adventurers with sublime views of the Faroe Islands.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.