In the city of Chartres, 55 miles southwest of Paris, Our Lady is honored under three titles, among them “Our Lady of the Underground”. All three titles have their origin at the spot today occupied by the Cathedral of Chartres.
On the spot where the Cathedral of Chartres now stands, the Druids raised a prophetic statue of a virgin, and called it Virgini Pariturae (virgin who would bear a son). The Druids were a fraternity of priests, religious teachers and judges who ruled the Celtic inhabitants of ancient Gaul (France now), Britain and Ireland. The Druids had a place of worship at Chartres, and even then, they had an altar in a grotto on a hill now occupied by the Cathedral; this altar was dedicated to the “Virgin who would bring forth a son” – traditionally also at that grotto there was a wooden statue to this (Pagan) virgin. The shrine of Notre Dame de Sous-Terre, is built on what was probably the oldest dedicated shrine to Our Blessed Lady anywhere in the world. In fact the shrine is even ‘pre-Christian’, being as it is the site of an original pagan temple from before the birth of Christ!
It is natural to wonder where the Druids got the idea of this virgin. There are several theories on the idea; they might have learned it from the Jews, who, after the conquests of Alexander scattered all over the earth [or they may have been a segment of the Jews themselves who kept their prophecies and traditions with them]; they might have received it from a revelation direct from God; they may have gotten it from ancient tradition running back to the early patriarchs and prophets. As one old story goes, in the year 50 B.C., the Druids heard of Isaiah’s prophecy: “Therefore the Lord himself shall give you a sign. Behold a virgin shall conceive, and bear a son…” (Is. 7:14). They instinctively knew that this would be the one true God who would prove their old gods to be mere idols, and so they ordered a statue of this unknown virgin and child to be sculpted and placed on the altar.
Regardless of whence it came, it is certain that when the Christian missionaries arrived in Chartres, they found the ancient shrine there. The Christian missionaries converted the shrine into one dedicated to the Virgin Mary, Mother of God. All down the centuries, through building, fires, and rebuilding of the several churches, the original Druid grotto was called Our Lady of the Underground, since it was kept in the crypt (underground) of the Cathedral of Chartres. In 1650, the grotto underground was walled up and, at that time, a small chapel was built close to the crypt, and the statue of Our Lady of the Underground was transferred to it.
In 1793, during the French Revolution, the revolutionists removed the statue and burned it, badly damaging the chapel. In 1857 the underground shrine was restored and a new statue carved of stone placed in it. So, Our Lady is still Our Lady of the Underground. And how fitting today that she has such a title; for so many of our people who suffer under many dictatorships must certainly worship in secret, they are of the “underground”, so to say, and have a Mother also thus titled.
Source: immaculate.one