This plot of old-growth forest is the largest surviving remnant of New York City's original woodland.

If it hadn't been caught in time, a flaw in the design of this Manhattan skyscraper could have led to its collapse.

Michael Jackson got Bad and Crocodile Dundee walked on heads in this iconic Brooklyn subway station.

When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

Four hundred granite steps were built into this massive rock by the National Park Service.

The original toys that inspired the beloved children's stories are on display at the New York Public Library.

A celebration of capitalism in Midtown.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

Quite simply the largest tree in the world (by volume).

London’s first road overpass is so old that it was originally built for horse-drawn carriages.

A devastating landslide accidentally created this tourist hotspot.

The oldest church in Mantua was buried for centuries under the facades of other structures.

The city of Parma's cathedral is home to one of the greatest illusionistic frescoes of the Renaissance.

This statue of one of the engineers who created the London Underground hides a ventilation shaft for the tube lines that run under the street.

One of London's lost rivers runs through a pipe over the tracks of this subway station.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

An early 20th-century bullring converted into a modern shopping center.

This colorful statue welcomes visitors to a Barcelona park.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

One of Madrid's oldest trees, with a long and colorful history, resides in El Retiro Park.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Commonly acknowledged as the only public monument to the Devil himself.

A lush indoor jungle fills this bustling Madrid transportation hub.

This one-time health resort was used by aristocrats around the world.