Chapel of Our Lady of the Miraculous Medal

Right in front of you, number 140 Rue du Bac looks like nothing special. A wooden door, two shops on either side, the usual bustle of Paris. But step through, and the city falls away. A stone passage lined with statues leads you quietly into a hidden chapel tucked behind convent walls, and suddenly you're somewhere else entirely.

On the night of July 18, 1830, a 24-year-old novice named Catherine Labouré was woken by a child who told her the Virgin Mary was waiting. She followed, and for two hours, she sat and spoke with Mary in this very chapel. Four months later, Mary appeared again, standing on a globe, her foot on a serpent, rays of light streaming from her hands. A voice instructed Catherine to have a medal struck in that image. Today, roughly 1 billion people worldwide are believed to wear it.

Catherine told no one. For 46 years she worked quietly with chickens and elderly residents in a suburban care home, and no one knew she was the visionary. Only on her deathbed in 1876 did she reveal the truth.

When her body was exhumed in 1933, it was completely intact. You can still see it here, resting in a glass case beneath the altar.

One more thing worth knowing: those 12 stars surrounding Mary on the medal? The designer of the European flag confirmed in 1987 that he took them directly from this medal, and the flag was adopted on December 8th, the Feast of the Immaculate Conception. So in a small way, every time you see that famous circle of stars, you're looking at something that began right here, in this hidden chapel on an unremarkable street.