The weathered grave of a medieval anchoress who walled herself up in a cell attached to a church.

A plaque marks the underground site of one of London's "lost rivers."

Marvel at this turn-of-the-century masterpiece that has been turned into a rather stately supermarket.

Once the largest unsupported dome in the world, beating out the Pantheon and St Peters in Rome.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

This pump on the bad side of Victorian London betrayed a horrifying revelation about the water supply.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

An unusual round church in London with a Templar past.

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

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

The television series' iconic giant foot was borrowed from this classical painting.

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

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

The "beautiful" equation predicting the movement of all electromagnetic particles is engraved in front of Newton's tomb.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

The largest of London's subterranean rivers and once a mad, bad center of London life.

Dictionary Johnson’s favorite feline.

On October 17, 1814, a 15-ft. wave of beer ran rampant through the streets of London.

London's smallest police station is barely the size of a phone booth.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

This chain of artificial lakes was an ideal test ground for the aircraft that would carry the "bouncing bombs" used by the WWII "Dambusters" squad.

The name of this tiny pocket park tucked between two buildings on Manhattan's Upper West Side is Latin for its location: "seventy-one."

Three hundred years of preserved Spanish colonial history in San Antonio.