Historic, 19th-century wagon wheel ruts cut into soft volcanic ash.

This trail leads to a mine that was used as a sanctuary during the Great Fire of 1910.

A breathtaking 19th-century trail overlooks Lake Tahoe.

Walk a trail through a historic Quaker town that outlawed slavery in 1777 and was a major waypoint on the Underground Railroad.

The longest non-mortared wall in the country is one man's tribute to his displaced Yuchi ancestor's five-year journey to her homeland.

A trail weaves through the verses of a poem illustrated by stone sculptures inspired by Native American pictographs.

A series of 33 stone markers maps an ancient 55-mile transportation route.

Many generations of travelers have passed through the steep, smooth walls of this canyon.

The high point on the 16th president's eponymous roadway is marked by a massive version of his head.

An architect's childhood fantasy treehouse made real.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.