A man-made island in scenic San Francisco Bay.

Radioactivity still cause for concern at this urban explorer's paradise.

Golden Gate Park's historic collection of plants.

This private residence was the template for one of the most beloved television homes of all time.

A monument to the love people have for their pets.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Scattered throughout London are ancient remnants of the city's former bounding wall.

Hear the quietest sound from across the dome.

An unusual round church in London with a Templar past.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Everyone from Mark Twain to Teddy Roosevelt has a pipe hanging from the walls of this historic chophouse.

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

Curious crustaceans support an obelisk from ancient Egypt that now stands in modern-day Central Park.

Plot your trip through the city on the sidewalk.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

A very classy 1920s-era bar right in Grand Central Station.

Walk over a 150 year old manhole.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

Mysterious 500-year-old tapestries depict a unicorn hunt.

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.