A trio of red, white, and blue stones embedded in the streets of Leiden are markers of medieval territory and law.

This 11th-century castle sits so low you can't see it behind the surrounding buildings.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

The location of the world's first telescope demonstration.

View the ancient remains of buildings and the ancient "River of Hades" before hopping on a train.

The fierce beast perches atop a pedestal marking where the historic City of London gates once stood.

A measuring mishap led to these artificial stone ladies losing their stomachs.

This mysterious and unique painting is filled with symbolism.

This macabre painting of a Shakespearean scene looks like something out of a nightmare.

A haunting painting meant to capture the calamity of World War I.

A gruesome and mysterious ancient sculpture of a pagan deity from the Roman occupation of Celtic Britain.

This intriguing Bronze Age artifact spent centuries hidden within a Welsh faerie hill.

A naturally mummified 2,000-year-old man.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

The beautiful, ornate weather station is the most popular geocache in Salzburg.

100 year tradition of fist fights, marked by marble footsteps.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

Each time a baby is born in Ghent, these streetlights flash in silent celebration.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The last masonry skyscraper ever built reveals a transitional moment in architectural history.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

Legend has it that this bronze orb, which sat atop an ancient Egyptian obelisk, once held the ashes of Julius Caesar.

An 18th century fountain and two columns are all that remains of Rome's forgotten river harbor.