A small village in two different countries.

The stately remains of Llywelyn the Great's mighty fortress.

An unexpectedly extraterrestrial room in a former Victorian resort club.

English parliaments were once convened by this ancient oak tree in the heart of Sherwood Forest.

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

An unusual round church in London with a Templar past.

In this medieval fish bowl, the carp weren't pets.

This iconic Peak District ridge was once one of the busiest roads in medieval Britain.

L. Frank Baum wrote part of the "Wizard of Oz" series in this wooden Victorian beach resort.

One of the earliest large-scale "hyper" roofs in the U.K. is now a derelict roadside attraction.

This home of a taxidermy hoarder is among the grandest and most singular of historic English estates.

A labyrinthine underworld of tunnels and caverns hides beneath the city.

It was once nicknamed "the most bombed hotel in Europe."

A 15th-century former coaching inn forms the implausibly grand entrance to a 1980s shopping mall.

A giant sculpture of the legendary "Salmon of Knowledge" celebrates the return of fish to Belfast's River Lagan.

The oldest working mechanical clock in the world.

The first archaeological site discovered by aerial photography.

The commemorative stone column conceals a secret laboratory.

The colorful stairs are made with marble from the world's major quarries.

The entire length of the border is marked by a 20-foot-wide slash through the trees.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

This stunning concert hall has become a symbol of Iceland's national recovery.

This suburban British town holds secrets that would have made the druids proud.

The English town of Mansfield likely got its name from this enigmatic breast-shaped mound rising abruptly from the earth.