The underground city of Naours is a former chalk quarry that served as a refuge for the inhabitants of the village during the wars and invasions that Picardy experienced. This site is located in the French town of Naours , 14 kilometers as the crow flies north of Amiens , in the Somme department , in the Hauts-de-France region . This underground refuge or muches (“hiding places” in Picard ) includes 28 galleries on which are distributed around 130 rooms, at an average depth of 33 meters under the hill. The height of the galleries varies between 1.60  m and 2  m  ; the temperature is constant throughout the year, at 9.5 ° . This underground city could shelter nearly 2,000 people. Throughout the galleries are the rooms of the different families. Also noticeable are the stables with the troughs, the ventilation chimneys and the smoke chimneys which stood out in those of the houses.