The ritual has been performed uninterrupted for nearly 700 years.

A mysterious carving from 17th-century London seemingly depicts a young boy sitting on a bread basket.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

The gigantic skull of a long-extinct species that once roamed the forests of England and Ireland.

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

Victorian-era Londoners really wanted to believe this 17th-century cistern was actually an ancient artifact.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

The pretty iron lamp is a reminder of the architecture underneath London's streets.

One of the few remaining examples of 19th-century London’s attempt to clean up its reputation.

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

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

This beautiful deer park was built so King Charles I and his court could go hunting while escaping a deadly plague outbreak.

Where condemned pirates met their grisly end at the gallows on the River Thames.

These ornate arches show how the course of the River Thames has changed.

The sumptuous ceiling was one of the last things Charles I saw before his execution.

The library houses an incredible collection of some of the world's most impressive books and manuscripts.

Tombstones and enigmatic inscriptions hide within a vault beneath a popular London arts venue.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

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

A Roman spa buried deep beneath the City of London.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.

Installed at a chaotic intersection, this gave London traffic cops a place to hang their heavy woolen coats.