Mined to a depth of 240 meters with a perimeter of about 1.6 km, the largest hand-dug excavation in the world.

A spectacular rainbow of stained glass makes the "Pink Mosque" one of the most beautiful in Iran.

Regency-era excess on the English Coast.

Rippling sand dunes frozen in the Arizona rock.

This astronomical clock is the second oldest in England.

It's believed King John of England stayed at this 13th-century castle before riding off to sign the Magna Carta.

The ruins of an abandoned medieval city where the last Byzantine emperor was crowned.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

This short pedestrian span is also known as the "Fairy Walking Bridge" because it looks almost magical.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The highest peak in all of England is plagued by dangerously fickle climate shifts.

This well-preserved Cistercian Abbey in a romantic pastoral setting has inspired artists like the poet Wordsworth.

This striking royal residence is the largest Renaissance-style castle in Scandinavia.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

Although it appears ancient and mysterious, the quirky folly was actually built 200 years ago by an eccentric estate owner.

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

One of the most well-preserved temples of ancient Egypt.

The world's largest collection of witchcraft regalia.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Overlooking a Scottish loch, this beautifully crumbling castle once inspired a poem by William Wordsworth.

The real life Hobbiton, this sheep farm has been forever transformed since being built for The Hobbit film series.

One of its engravings is believed to be among the first representations of medical and surgical instruments.