The ritual has been performed uninterrupted for nearly 700 years.

An architectural oddity hides in plain sight on this iconic London bridge.

A collection of comics, graphic novels, animation and caricatures devoted to exploring this often overlooked art form.

The Great Fire of London and the regulation of one-way streets both started in this alley.

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

The commemorative stone column conceals a secret laboratory.

This museum tucked below a charming cafe gives a brief snapshot of photographic history.

The pockmarks across the building's facade are remnants of the Blitz.

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

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

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

This overlooked street light once served as a KGB dead letter box.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

More than a million titles fill the labyrinthine shelves of this prestigious private library.

This ancient Egyptian obelisk still bears the wounds of World War I.

This long-hidden space above Westminster Abbey now displays the battle gear of the legendary King Henry V.

A lasting remnant of The Blitz.

A lonely beacon, precariously perched atop a remote sliver of rock.

A replica of the Liberty Bell rang daily from West Berlin's City Hall throughout the Cold War.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

A small square plaque marks a failed assassination attempt that could have changed history.

A preserved Nazi labor camp now has a Holocaust museum on site and memorials to the thousands that died while imprisoned at the camp.

The largest brick bridge in the world.

The last bastion of Roman presence north of the Alps looms over a German town.