The "Black Arch" guards the entrance to the picturesque Glens of Antrim.

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

This Italian-style temple replica has been threatening to fall off the Irish coast for hundreds of years.

The only monument to name all of the passengers and crew who died on the RMS Titanic.

For part of the year, this innovative greenhouse is painted white to keep the plants from getting scorched.

This Victorian-era public house has set the standard for pub-style elegance for over a hundred years.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

Northern Ireland's Brobdingnagian stepping stones.

The arch marks the beginning of the road for northbound travelers.

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

These 90-year-old murals of local kings, Vikings, and outlaws hide in plain sight in a beautifully baroque shopping arcade.

When it came to designing his own small office building, the eccentric architect wasn't afraid to show the world what he could do.

The oldest inn in England served brew to the crusaders.

This Victorian marvel of engineering and artistic prowess is nicknamed the "Cathedral of Steam."

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

The ancestral home of beloved English poet Lord Byron has a bizarre history.

The largest oak in England is said to have been the hideout of Robin Hood and his Merry Men.

Eighty million natural history specimens call this gargantuan museum home.

The largest Commonwealth memorial to the missing and dead of the Battle of the Somme.

Hilltop garden on the site of an old fortress overlooking the Mediterranean Sea.

The evocative ruins of a medieval village.

This impressive chasm is one of the longest natural underground cavities in the world.

This stone quarry was used to make axes and other tools more than 6,000 years ago.