Longitude 50.034296. Latitude 2.280462.
The Underground City of Naours is thought to date from the 3rd century AD.
The town of Naours is in the far north-east corner of France, near the border with Belgium.
The Romans were the first people to dig into the plateau back in the 3rd century and in subsequent centuries locals continued digging out the caves and grottos.
Perhaps early Christians hid below the ground in order to escape their persecutors – there are nooks and crannies in which to hide and set up chapels.
In the 9th century AD Viking invaders dwelled in these underground caves.
In more recent times, local peasants made their homes in the vast network of caves turning the place into a large underground settlement, replete with extensive passageways and more chapels, and even water wells.
Some 3,000 peasants lived in the underground settlement, and even farm animals were kept underground, according to Naours historians.
There are three chapels, including the Rotonde de la Sainte Vierge (Chapel of the Virgin), where upon a rocky ledge stands a statue of the blessed Virgin Mary holding baby Jesus.
The other chapels have similar statues.
The entrance to the underground city was re-discovered by a local parish priest, Abba Danicourt, in 1887.
In total there are 28 galleries and 300 chambers or rooms.
During the WWI soldiers fighting on the battlefields of the Somme are said to have lived in the caves and, later during WWII the German high command apparently used the cave system for their headquarters.
One can still see the graffiti that soldiers have left behind on the walls.