"Mary King’s Close is part of the city’s famed underground city. In 1753, after Edinburgh had suffered from the plague and, in turn, overcrowding, the city built a Royal Exchange building (now the City Chambers) where merchants and traders could sell their wares away from disease and filth. They decided to erect this building atop the existing streets, thereby entombing closes like Mary King’s forever. Although it's fully underground today, it still sports eight-story tenement buildings, complete with doors, shuttered windows, gutters, and even viewable rooms and former stores. It’s accessible by tour only." - Freya Herring