The fire inside this temple has burned for more than 1,500 years.

A lush indoor jungle fills this bustling Madrid transportation hub.

A bizarre house filled with an astounding array of collections.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

Carved initials which are nearly 500 years old preserve the deposed Queen's presence at Hampton Court Palace.

This overlooked street light once served as a KGB dead letter box.

This monument is dedicated to a young boy who survived a disaster that forced Edinburgh to reevaluate its building codes.

The extremely grey columns of one of Mexico City's most iconic beltways are slowly gaining a bit of color.

Home of a French nobleman's short-lived attempt at raising cattle in the Badlands of North Dakota.

Local legend says Isaac Newton built this footbridge without any screws, bolts, or nails.

Cat art as far as the eye can see.

An abandoned railroad tunnel is now filled with bioluminescent bugs.

The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.

If you like Art Deco you will love this bridge.

An old curiosity shop holds on to a centuries-old tradition of manually-distilled rose water.

One man's homage to the sun continues to grow like a glass fractal.

A replica of the flagpole that gave a frontier town its name.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

This precariously perched fortress was once ruled by a crow-worshipping baron.

A historic observatory precariously perched at the "Top of Europe."

A forest of immensely tall and unusually straight oak trees planted nearly 200 years ago to build naval ships that never came to be.

The pretty iron lamp is a reminder of the architecture underneath London's streets.

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