Scattered throughout London are ancient remnants of the city's former bounding wall.

The barrel-made lookout from Shackleton's final ship is tucked away in the crypt of one of London's oldest churches.

The ritual has been performed uninterrupted for nearly 700 years.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

This unassuming alcove in London’s famous Tower Bridge once served to capture, store, and display dead bodies from the River Thames.

A commemorative plaque at the door pays tribute to an "American Patriot" known for his betrayal.

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

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

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

A bronze bust commemorates the heroism of the secret agents who led covert operations against the Nazis.

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

Never actually a tree at all, this spot was the site of London's public hangings for nearly 600 years.

This pub was 238 years old when it decided to revamp its image: It started serving Thai food.

According to legend, this tomb holds the secrets to time travel.

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

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

Since 1887, this old-school shop has stacked its shelves with extraordinary coffees and teas.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

This pub built its reputation pouring post-shift pints for employees of the cemetery with which it shares a wall.

The metal frame is all that's left of a wicker sculpture which once towered over the M5 motorway.

One man's attempt to stay one step ahead of the church.

Little Red Lighthouse under the George Washington Bridge.