The residents of Dartford, England, erected one of the world’s most expensive walls of stone around 1579. They used more than 530 blocks of rock to reinforce the western perimeter of what at the time was known as King Henry VIII’s Manor House. The stone itself is not that exciting; it’s a 1.3- to 1.8-billion year-old, black and white gneiss. What makes the stone notable is how it ended up in Dartford, about 20 miles southeast of London.
The black rock had come fro… (View original article)