A forsaken wonder in the middle of the East Side neighborhood.

One of Frank Lloyd Wright's greatest—and favorite—architectural masterpieces was almost lost.

The site of William McKinley's tragic assassination is only marked by an underwhelming boulder.

The only boathouse Frank Lloyd Wright ever designed was also the only unbuilt structure in his famous Wasmuth Portfolio, until 2007.

Small ship votives hang from the vaulted ceiling of this port-side church with a Latin inscription on the wall.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

A labyrinthine museum chronicling the history of African culture in Brazil.

This park feels like a lush little jungle full of wildlife nestled within São Paulo.

This singular art museum in São Paulo is unique inside and out.

One of São Paulo's tight urban intersections has become a haven for graffiti artists ever since a single Batman started the trend.

Straight out of a nightmare, barcode-faced babies climb up and down Prague's television tower.

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

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

This museum was invented in a novel before being made real by the author.

1513 Turkish world map, full of European state secrets and snarky commentary.

A marvel of Byzantine engineering under the streets of Istanbul.

Though strikingly beautiful, Seattle's other railway station is now largely forgotten.

The first green space constructed on an elevated viaduct.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

One of Amsterdam's narrowest houses is located right across the canal from its widest.