This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

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

The final resting place to 300 Victorian-era pets hides inside the city park.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

A cluttered and astounding collection of antiquities and curiosities.

An unusual round church in London with a Templar past.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

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

The yawning maw of this pagan visage is said to bite off the hands of liars.

The studio built by fascists in the hopes of "reviving the film industry" with the occasional propaganda film opportunity thrown in.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

Jesus' footprints and the first catacombs in the world.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The final resting place of the poets Shelley and Keats.

2300-year-old Roman road connecting the empire.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Manhattan's Thirteenth Avenue was made on landfill then deliberately destroyed — apart from one small, obscure block.

The one-time epicenter of American songwriting is now a little remembered Manhattan commercial block.