London's only public statue of the much-married monarch adorns the gate to St Bartholomew’s Hospital.

This plaque in one of London's oldest public hospitals commemorates the first meeting of two of Britain's most famous literary heroes: Sherlock Holmes and Dr. Watson.

A portly statue of a golden boy commemorates an unusual cause of the Great Fire of London: the sin of gluttony.

The ruins of a church destroyed by both the Great Fire of London and the Blitz, now turned into a peaceful garden.

On the eve of a condemned prisoner's death, this bell rang 12 times outside their cell.

Buried for centuries, this hidden cellar is all that remains of London's medieval Whitefriars Monastery.

Public access to clean drinking water was an instant hit among the masses.

A mysterious pair of mice eating a piece of cheese is London's smallest public sculpture.

The commemorative stone column conceals a secret laboratory.

Tucked between a side street and a theater, this arch once led to a prestigious riding school, and now opens to a courtyard and community garden.

An ornate private entrance to the Vienna subway built specifically for the emperor.

A patriotic medieval knight in driven-nail armor raised money for widows and orphans of WWI.

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

These 13th century documents come housed in 18th century shelves organized by a 19th century historian.

A giant glider—designed by the father of the Rubik's Cube's designer—now soars within a shopping mall.

Madrid's last horchata kiosk is a blue-and-white beacon of refreshment.

This amazing abuela became a diehard metal fan late in life and an icon of Madrid's '80s rock scene.

A 16th-century Andalusian palace.

Its appearance in "Game of Thrones" may spur on the long-awaited restoration of this medieval shipyard.

An eerie collection of the surviving structures from a past celebration of the future.

The current seat of the Parliament of Andalusia was once the epicenter of the Great Plague of Seville.

The final resting place of the great navigator, or maybe his brother.