The designer of this railway tunnel added a birthday present for himself.

The last remaining example of the boatmen's perches that once dotted the south bank of the Thames.

Is this the most Portland place ever?

A small village in two different countries.

A curious little museum dedicated to the furry feline in the cat haven that is Old Town Kotor.

A whale rib was used to advertise the store by the arch that offered exotic goods from far away.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

A mapping error in the 19th century made loggers think this section of the forest was underwater.

A celebration of solstice followed by a fiery purging of evils.

A cross marks the spot in a small Scottish village that claims to be the exact center of the country.

A remarkably well preserved tower dating all the way back to the Iron Age.

Ralph Waldo Emerson spent two years living here decades before it became a Frederick Law Olmsted-designed park.

The construction of a tram line unveiled hidden remnants of the old medieval city.

The world's largest prehistoric copper mine had 30,000 animal bones scattered throughout the maze of passageways.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

Over 3km of caverns and caves at the Switzerland-France border contain the largest underground river in Central Europe.

The world's oldest known salt mine.

A marvel of Byzantine engineering under the streets of Istanbul.

Free candle-lit art gallery, accompanied by a live piano score.

Running since 1864, this clock has yet to be wound, one of the longest-running science experiments known.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

Rent out a glass igloo to watch the Northern Lights like you live in the future.