The Grand Mosque of Paris was built in 1926, to honor the 100,000 North African Muslims who fought and died for France during World War I. The imam was Kaddour Benghabrit.
French music hall performers achieved superstar status such as Maurice Chevalier, Josephine Baker, and Edith Piaf. Another one was Selim Hilali, who was a Jewish singer. (Josephine Baker’s first husband was a Jewish sugar merchant, but she changed religions in her further marriages. Maurice Chevalier was indirectly accused of being a Nazi collaborator during World War II, but oddly enough was a prisoner in a German prisoner of war camp during World War I.)
During World War II, after France surrendered and was occupied by Nazi Germany, Imam Benghabrit and the Grand Mosque of Paris took in and hid Jews from the Gestapo. In France, a birth certificate was issued by both the state and a house of worship. Imam Benghabrit issued birth certificates for Jews from the mosque, and one of those issued was to Selim Hilali. Imam Benghabrit went as far as creating a fake tombstone for Selim Hilali’s father in the Muslim cemetery. Eastern Orthodox Christians, Jews, and Muslims have their houses of worships and cemeteries on consecrated ground. Below the city of Paris are limestone catacombs, and one was below the mosque. The Grand Mosque went as far as placing electrical lighting in the catacombs below the mosque, so they would blink and warn the Jews hiding that the Gestapo was in the mosque, so they could move out to further catacombs. This went on all throughout World War II.
Imam Benghabrit died in 1954, and was encrypted in the Grand Mosque of Paris. Selim Hilali took out an ad in one of the French newspapers, crediting Imam Benghabrit for saving his life, and those of numerous other Jews in France during World War II.
What can be done when one goes to the Grand Mosque of Paris, is to stack stones where Imam Benghabrit is encrypted in the Jewish tradition, and pour water during the Feast of Eid after Ramadan, in the Muslim tradition.