Mary King's Close is a historic underground street in Edinburgh, Scotland, known for its well-preserved buildings and rich history. It dates back to the 16th century and was once a bustling area filled with homes, shops, and businesses. The close was named after Mary King, a prominent merchant who lived there. Today, visitors can explore the close through guided tours that reveal its fascinating past, including stories of daily life, the impact of the plague, and the area's eventual decline. The site offers a unique glimpse into the life of Edinburgh's residents centuries ago.