This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

The world's largest maze is a nature park with nearly 200 decision points.

The remains of the observatory of the Danish astronomer who first measured the speed of light.

Six beautiful wooden giants are hidden around Copenhagen.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Old Danish castle immortalized in Shakespeare's Hamlet.

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

Beneath Denmark's Højbro bridge, a bronze merman and his seven sons forever mourn for the mother and wife who left them for land.

Copenhagen's celebrated theme park and gardens.

The gilded, masterful astronomical clock will calculate time, dates, and planetary positions for thousands of years to come.

The world's first permanently occupied mountain-top observatory continues to report on the stars.

Flashy signs from Las Vegas’s past find their final resting place at this unusual graveyard.

The history of the tea trade is told in bas-relief on this historic pair of Boston doors.

The site of one of the strangest disasters in history—a wave of deadly molasses traveling at 35 mph.

Stolen goods adorn the organ at Old North Church.

The first bell ever cast in Boston was cast by Paul Revere...and sounded terrible.

The site of Paul Revere's historic two lantern warning.

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

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

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

An collection of Chinese propaganda posters from 1949 to 1979.

A total of 999 stairs lead visitors through a massive hole in a mountain known as the Gateway to Heaven.

For those with no fear of heights: a skywalk 4,700 feet up on a Chinese mountain.

The latest in a series of long glass bridges suspended at terrifying heights.