A relief that wraps around the concourse of Los Angeles's World Trade Center marks one of the city's failed urban design plans.

A series of concentric circles represented a bold new experiment in socialist urban planning, and it notoriously difficult to get around.

With its webbed walls and bright red coloring, Calgary's iconic bridge looks like a finger trap puzzle stretched across the river.

The most unusual block in Brasília.

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

The soaring gondola lines form the longest aerial cable car system in the world.

The world's largest bicycle shelter can hold more than 12,500 two-wheelers.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.

An ingenious solution to a tricky engineering problem, this spiraling bridge takes drivers for a dizzying spin.

At just 25 inches at its narrowest point, it's one of the tightest streets in the world.

An oversized, oddly designed pedestrian overpass has drawn comparisons to a commode for pachyderms.

This abandoned viewing platform has become a monument to unnecessary government spending.

Despite many attempts to finish this overpass, it has been abandoned since the 1970s.

The highest pedestrian bridge in Singapore looks like a series of undulating waves rising between two public parks.

A giant roundabout made up of six smaller roundabouts can befuddle the uninitiated.

This bridge's unique architecture honors nautical heritage and encourages self-awareness.

The mastermind behind this palatial hotel perished on the Titanic weeks before its grand opening.

This psychedelic tourist trap is a leisurely descent into madness.

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

Hamburgers are intensely proud of their tunnel beneath the river.

This colorful creation wasn't always a welcome part of Toronto's Moccasin Trail Park.

In Hong Kong, a fairytale flower tunnel is hidden within the gardens of a public housing complex.

The romantic botanic tunnel feels like a well-kept secret.

A repurposed railway tunnel with otherworldly acoustic characteristics.