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

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

A plaque hangs near the execution place of the Scottish Independence leader famously depicted in "Braveheart."

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