One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

360° views of the city plus five floors of optical illusions and hands-on science.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

When Azorean green tea meets volcanic hot springs water, a luminous brew is born.

A fortress off the West coast of Portugal that dates back to 1502.

You can cross from one country to another in a single hop on this little bridge.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

A Manhattan courthouse hides a small but scathing memorial to Holocaust injustice.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

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

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

Just a man taking his prehistoric pet for a stroll.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

This was the first homestead registered after President Abraham Lincoln signed the Homestead Act into law.

The oldest candy store in the world has been selling traditional sweets since 1827.

This ancient market is often referred to as the oldest shopping mall in the world.

A library where thousands of books explain how to avoid another Great Recession.

This institution celebrates the happy accidents of uncommon sticktoitiveness.

The two-cell building in Nebraska was briefly owned by a teenage boy and then a Hollywood dummy.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.