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

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

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

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

London's amazing modernist public square that never was.

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

This unassuming building produced some of the world's most famous bells.

This magnificently macabre shield shows the power of chivalrous love in medieval times.

This intriguing Bronze Age artifact spent centuries hidden within a Welsh faerie hill.

This mysterious and unique painting is filled with symbolism.

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

"We gonna rock down to Electric Avenue, and then we'll take it higher..."

It's a mystery why these remains were found with no traces of their bodies in sight.

A gruesome and mysterious ancient sculpture of a pagan deity from the Roman occupation of Celtic Britain.

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

One of the figures in this Celtic sculpture continues to puzzle archaeologists.

This hospital helped pave the way for treatment that drove down child-mortality rates in 19th and 20th centuries.

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

A fully functional, 200-year-old remnant of the time when Brixton was mostly fields.

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

This Viking gravestone carved in a rare runic style was dug up from a London churchyard.

This innovative steam machine was no doubt the most famous of the pioneer locomotives.

This religious museum resides in a church crypt next to the founder's house.

A statue of the original Pearly King is hidden in a church's crypt.