This nine-story building can be played like an instrument.

The largest stone circle in the world has ended up bringing up more questions than it has answered.

There’s a hidden military meme engraved on the World War II Memorial.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

Climb inside an iron crystal magnified 165 billion times its normal size.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

It is said the legendary wizard once lived in this sea cave beneath Tintagel Castle.

Yo, Adrian!

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.

The highest point in North Carolina and the United States east of the Mississippi River, Mount Mitchell is named after argumentative explorer Elisha Mitchell.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

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

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

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

The mysterious megaliths have enchanted and intrigued visitors for thousands of years.

A 6th-century stone lies at the site of the mythical battle waged between King Arthur and his nemesis Mordred.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

The tech giant built three enormous glass orbs in Seattle so employees could work inside a rainforest greenhouse.