A former Royal Observer Corps underground observation post is located in the sand dunes to the east of Quebec Road, Mablethorpe. The post is believed to have been opened in 1961. Access was through a 2ft square hatch on the surface, where an associated air vent would also have been visible. A ladder would lead down the concrete shaft to two rooms; the first being quite small and used to house the chemical toilet. The second, much larger monitoring room measured approximately 15' by 7'6'', and would have been staffed by three observers. The post remained in use until 1991, when it was closed, the shaft was fileld with concrete and the structure was buried. Some sand has since eroded, exposing the western end of the monitoring room, although access is still impossible. {1}{2}