This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

Hundreds of thousands of ancient documents offer a unique glimpse into Jewish life in Cairo.

Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

This ancient structure is widely thought to be the oldest intact pyramid in the world.

The oldest tourist graffiti in the world helped archaeologists identify the Pyramid of Djoser.

This earthwork installation sits on a grassy hill, celebrating Iceland's past and present.

An alley way dedicated to graffiti and street art is a constantly changing street gallery.

"the sweltering inhabitants of Charleston and New Orleans, of Madras and Bombay and Calcutta, drink at my well . . . The pure Walden water is mingled with the sacred water of the Ganges."

Location of the first public performance and singing of the "Battle Hymn of the Republic."

The largest body of water in Massachusetts annihilated four small towns just to slake Boston's thirst.

This supermarket is suspended 25 feet above an interstate highway.

Second largest wastewater treatment plant in the country.

Memorial to a beloved puppeteer as well as all street performers.

On a former island, this old fortification once used to protect the Boston Area and started Edgar Allan Poe in his military career.

Impossibly life-like natural history models created out of glass by a father and son.

This cemetery served as the only official burial grounds in Cambridge for nearly 200 years.

Three prestigious academic collections come together to create a world-class natural history museum.

This hidden labyrinth offers walkers some brief peace of mind.

This tiny, painted door at the base of a tree stump has been a fixture of the Harvard University campus for decades.

A unique columnar residence built in the 19th century.

The statue of John Harvard isn't actually John Harvard—or even, technically, the founder of the school.

A Harvard-area eatery preserves the uncovered tiles of its century-old predecessor.