A short ferry ride east of London, a picturesque lawn welcomes visitors to the sprawling grounds of the Maritime Greenwich World Heritage Site. At night, a bright green beam of light projects over the lawn, illuminating the Prime Meridian from the Greenwich Observatory up the hill. Five hundred years ago, this scene looked quite different. Back then, the lawn was a tiltyard, a rectangular field used for jousting and comprised of layered plaster and gravel, topped with sand and split down the middle by a wooden barrier called a tilt….
