The "Seinfeld" diner.

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

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

Peek through the gates at this oasis from the city, full of Old English charm.

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

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

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

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

One of only two commuter aerial tramways in the United States.

New York City's smallest piece of private property.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

Elevated freight railway turned wildly successful urban park.

A crumbling hospital from the 1850s on Roosevelt Island.

The bones of this aquatic dinosaur turned to opal over the centuries and the beast's remains were almost sold as jewelry.

This Franklinford, Australia site was once home to one of the remotest churches of its faith—in the fictional world of the Kcymaerxthaere.

The site of good faith and good nature in the fictional world of Kcymaerxthaere.

A land of debatable treasure.

Many generations ago, it was said that one could find celestial splendor in a lush meadow not far from this very marker according to the lore of the fictional world Kcymaerxthaere.

Though considered an eyesore by some, this boxy Brutalist high-rise plays a significant role in Sydney's past.

World War II ended before these tunnels built to protect vital oil from Japanese bombs were ever used.

Taxidermy of the racing horse with a huge heart, who inspired hope in the Depression.

This giant dish located in a sheep paddock was the primary receiver of Apollo 11 TV transmissions.