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

Old Danish castle immortalized in Shakespeare's Hamlet.

A natural wonder in south Denmark.

Opulence and fantasy collide in this royal chair which is supposedly made with unicorn horns.

This secret collection of the strange and occult was rediscovered in a forgotten room of an old house.

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

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

Copenhagen's celebrated theme park and gardens.

A striped 12th-century basilica sits in the countryside of Sardinia.

Psychoanalyst Carl Jung reported a paranormal experience after visiting this mosaic-lined Roman baptistry.

In Florence's great Duomo, a 26 foot fresco honors a mercenary famous for attacking Florence.

An incredible mosaic-lined monument said to have held the remains of an ancient Roman empress.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

This cathedral hides a sculpted dog that determines your fate and an unexploded shell from World War II.

Built to repay the sins of the father, this church is home to one of the most valuable works of Western art.

Fortified medieval tower house with lovely roof garden.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Italian poet Dante Alighieri is entombed in this small mausoleum in Ravenna, and his hometown of Florence has never been too happy about it.

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

An ancient rogue artist community hidden next to one of the world's most glitzy and glamorous cities.