Cryptic messages embedded in the New York City sidewalk.

Oldest building in California still in use.

San Francisco's newly reopened hands-on science museum.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

This industrial area was the dumping ground for massive amounts of trash, some of which washes up as tiny bits of sea glass.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

Copenhagen's celebrated theme park and gardens.

This oddity shop contains everything from antique tools to a human skeleton.

It was once used as a classroom to teach mining skills to local high school students.

The mayor made the declaration in 2004.

This trail leads to a mine that was used as a sanctuary during the Great Fire of 1910.

This playground sculpture of an icon from the past is dedicated to the children of the future.

Where beautiful signs live on forever.

Once strictly off-limits, this lower level housing curious and priceless vehicles of the Petersen Automotive Museum is now open to the public.

Scores of vintage street lamps shine along L.A.’s Miracle Mile.

The White House Situation Room was taken apart in 2006 and shipped to the Ronald Reagan Presidential Library.

A basement full of treasures lies beneath this inn that has worn many hats throughout its 140+ years.

From Japan to Italy, this California park explores the world's cultures through their gardens.

The world-record holder for the longest bridge stretching continuously over water.

An absolutely beautiful 200-foot stained glass installation traces the evolution of knowledge.

Elevated freight railway turned wildly successful urban park.

The "father of immunology" used this humble hut to offer the local people some of the world's first free vaccinations.

An extensive collection of fine art devoted to man's best friend.

This enormous banquet-themed artwork honors over 1,000 notable women throughout history.