Geothermal waterfalls in Tuscany.

Largest necropolis in the Mediterranean.

A sculpture serving as an homage to Pope John Paul II.

2300-year-old Roman road connecting the empire.

The celebrated eyesore created by starry-eyed sweethearts.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

A modern sliver of architecture in Roma.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

Dozens of padlock-trees along the Moscow River.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

The world's most active stratovolcano is almost always erupting.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

A church of bones, decorated with 40,000 human skeletons.

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

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

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

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

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.