These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Christ's blood allegedly preserved in a Belgian town.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

A series of playful yellow penguins share a serious message about the environment.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Macabre astrological automaton clock dating to the late 1400s.

Go inside to really appreciate this 500-year-old technological masterpiece.

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

The shop where the girl who inspired the beloved character once bought sweets is now a book-themed commercial curiosity.

A theatre built to house the rowdy Oxford graduation ceremonies became the stage for a debate about God's existence.

This bridge later moonlighted as a local jail.

Famously misunderstood wonder of the ancient world

The accidental discovery of this gilt bronze head led archaeologists to find the Roman Baths in the city of Bath

The oldest floral clock in the world still functions today.

The tomb of one of Scotland's bloody historic villains is a magnet for bumbling desecrators.

The most loyal of little dogs, or a Victorian era publicity stunt?

Protecting the dead from opportunistic body snatchers.

The final resting place of soldiers' loyal canine companions.

Sprawled across the Great Hall ceiling are various constellations and images relating to the zodiac.

A beautiful Greco-Roman structure houses a well once believed to have healing powers.