This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

A ghost town at the airport is now a refuge for blue butterflies.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

The lighthouse central to the 1980s horror classic "The Fog" is, in fact, located in one of the foggiest areas of the Pacific Coast.

The southernmost outpost of the Russian Empire in colonial America.

The longest and widest floating bridge in the world.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

Shiny Brutalist box commemorates a pioneer of electricity and houses a railway transformer.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

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

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Famously misunderstood wonder of the ancient world

Its dark depths conceal millions of rare, delicate crystal formations.

Each summer, the migratory bats living beneath the bypass form "batnadoes" at dusk.