Get The Explorer's Guide to Inventing the World

Peek inside this sandy mailbox and you'll spot kids' letters to Santa.

Britain's only herd of free-ranging reindeer.

The first space rock known to have struck a human.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.

A meandering boardwalk across the bogland leads to a "stairway to heaven" with sublime views.

A monument to the Mohawk people stands along an old Native American trade route.

Morocco's Argania trees are infested with nut-hungry goats.

A memorial for an outsider theorist who believed that the planet is actually hollow.

A rare cliffside vantage point of Lake Michigan with an explosive history.

Glass-fronted lifts give riders panoramic views of the skyline and the sensation of floating above Hong Kong.

Atop one of Windhoek's most popular eateries is a monument to Namibia's most resilient vehicle.

This cave complex might provide a link between the Neolithic and the Classical Greek period.

A lone traffic cone perched on a ledge has remained unmoved since at least 2011, unofficially earning the status of a tiny Chicago landmark.

A hidden canyon deep in the woods of Indiana offers visitors a spectacular experience in nature.

Legendary pedestrian bridge in the centre of Romanian city Sibiu.

The overgrown remains of a folly temple/playhouse, in an unmaintained section of a Dupage County Forest Preserve.