A retro walk through the history of the tube.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

Because sometimes you need to make a batch of frites even when the stores are all closed.

The world's largest floating loon bobs in the lake to kick off an annual festival.

A charming Spanish village sits atop this natural limestone overpass.

This magical place built as an astronomical center starred as a James Bond villain's lair.

A hidden tunnel leads to a medieval queen's shrine buried beneath a parking lot.

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

A tiny collection of traditional Japanese woodblock prints, open only when the owner feels like it.

A secluded natural oasis hidden deep along a rainforest trail.

Brazil's only museum dedicated to the art and evolution of tattoos.

This museum tucked below a charming cafe gives a brief snapshot of photographic history.

This iconic tattoo shop has its own onsite museum with artifacts from the early history of modern body art.

There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

To enter the lower hall of this temple, you must first walk through a dragon.

This 2,000-year-old tree inspired the nursery rhyme "Rock-a-bye Baby."

A galaxy of glowworms—larvae of a gnat—hides deep in the belly of these caves.

Legend says the goddess this shrine honors curses any couples that pass by.

The Tudor-style cottage in the middle of the square is not quite what it seems.

The tower in this 1,000-year-old mud-brick village seems to vibrate for no apparent reason.

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

Five varieties of trees with custom-designed grates around the trunk are planted along the route of the Seattle Transit Tunnel.

A science fiction-inspired apartment building designed by a famous Spanish architect.

Long before air conditioning, Persian architects found an ingenious way to cool off.