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

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

This tunnel entrance is built to resemble a grand castle but no one is quite sure why.

An unassuming churchyard is the resting place of a pioneering surveyor and reluctant namesake of a mountain.

Centuries of crashing waves carved out this small hole in the rock, which lights up at certain parts of the year.

A stone, covered in metal, commemorating an event that happened somewhere else a thousand years ago.

This Underground station has been a popular filming location for decades, even before it closed.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

This sculpture marks the spot where one of the greatest Roman rulers was proclaimed emperor.

This hill and tower are steeped in legend, from King Arthur to the Holy Grail.

The Great Fire of London and the regulation of one-way streets both started in this alley.

An Iron Age hillfort rooted in Arthurian legend was made famous by musician Peter Gabriel.

Barcelona's only remaining tram system takes riders to the Tibidabo funicular.

The world's first combination ski slope and power plant.

This aircraft museum is home to one of just three Halifax bombers in the world.

The much-beloved mascot of a local museum.

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

Occupied for six centuries by Franciscan Order nuns, this monastery is an amazing ode to Catalán Gothic architecture.

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

The spot where Oxford garnered its name was also home to a medieval philosopher and includes a house covered in statues.

A 1950s beatnik coffee house, turned 60s counterculture hotspot, turned modern music venue.

This incredible viaduct was part of the Victorian railway boom and helped the Midland Railway navigate tough terrain.

This small interfaith chapel lies not far from the rim of the Grand Canyon.