One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Found art has transformed this Pittsburgh neighborhood into a psychedelic dream.

This church in Pittsburgh is home to the largest collection of religious relics in North America.

A take-out restaurant that only serves cuisine from countries with which the United States is in conflict.

Long hidden under grime, the politically radical murals of a little known Yugoslavian master are finally getting their due.

This small New York museum examines Chinese history from its origins right up to its arrival in the city.

Tucked in the back of this amazing antique store is an important piece of medical history.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

This floating garden in the sky is straight out of a fairy tale, but the real thing is nothing short of magical.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

The ruins of an 800-year-old monastery boasts the tallest round tower in Ireland.

Obelisks and stone pineapples in the Irish countryside.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

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

The earliest known map to show America, discovered by accident at a Paris bookshop.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

The remains of a Rockefeller's lush Italianate estate hidden in the underbrush on the coast of Lake Michigan.

All of Chicago's wood-paved streets are long gone but two alleys remain.

Half-sized replica of the Leaning Tower of Pisa built to honor Galileo.

A six-story-tall golden pyramid, surrounded by a moat.

Nonprofit art center that promotes outsider, intuitive, and self-taught art.

An Argentinian businessman facing terminal cancer built this whimsical medieval village using salvaged materials.

These warring psychedelic crags commemorate an unsuccessful military operation.