A 19th-century time capsule of travel, fiction, and historic texts still available to the public.

The ancient ruins of an extinguished city amidst the bustle of a modern one.

In Twickenham sits a small whitewashed castle that inspired Mary Shelley's 'Frankenstein.'

An alien landscape on the banks of the Aegean Sea.

This Parisian fountain is a little bit fantasy and a little bit nightclub.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

A standing relief of a Norman knight whose posture marks him as a Crusader.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

Once the longest bridge in Ireland, this rusting span sits abandoned and overrun by nature.

Huge standing stones mark a site of megalithic mystery.

This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

A remarkably intact castle that once was the largest in Ireland.

These Pre-Columbian petroglyphs contain representations of birds, deer, hunters, and even some early Native flute players.

Legends surround this jagged rock formation in the New Mexico desert.

Once a menacing challenge for trailblazers, this trail is now the most scenic drive in Utah.

A trio of giant wooden megaphones turn up nature's volume in this Estonian forest.

A place as enchanting as the journey to reach it is harrowing.

A bathhouse from the second Islamic Caliphate decorated with frescoes of constellations, pleasure gardens, and naked ladies.

A tower built by an emperor for an antelope.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

One of Hungary's most influential places of learning is also home to one of the world's most beautiful libraries.

One of the largest necropolises in the world is home to a stunning array of historic Middle Eastern tombs.

The remains of what was the most important religious complex in coastal Peru for over a millennium.