An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

The strikingly modern structure stands out among the brick buildings speckling the Harvard Business School's campus.

A 1920s home transformed into an immersive art experience, where every room is a portal to another realm.

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

This Chinese museum proves that it's a watermelon world, we're all just living in it.

This site commemorates the former inn and restaurant where the chocolate chip cookie was first crafted.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

The only place where can you share a seat with the bums of the Fab Four.

An enclosed rotunda at the Henry Art Gallery in which viewers can look up and see the uninterrupted sky.

A lush Seattle garden designed by the same landscape architects responsible for New York's Central Park.

A more than 260-year-old crypt built on Boston's oldest English burial ground.

A New Zealand couple's shell-adorned home living room, now on display at the Canterbury Museum.

The ruins of New Zealand's largest classical-style church.

One of the largest collections of traditional Māori artifacts in New Zealand.

An unusual and powerful memorial in which earthquake victims are remembered by empty white chairs.

This aluminum “stairway to heaven” has impaled at least a couple of birds.

Historical figures from New York City's Catholic community reside in Midtown.

The rough and tumble president's childhood home displays the shirt he was once shot in and the speech that saved him.

During the holidays, a vintage subway train whisks New Yorkers back in time.

A crumbling hospital from the 1850s on Roosevelt Island.

The home of aviation trailblazers, in a remote corner of the big city.

The famous author's cottage hideaway.

The tiniest little stage in New York.