Marseille, that great and ancient Mediterranean port of France, is ringed by mountains, and for generations the high ground to the east has been claimed by the Catholic basilica of Notre Dame de la Garde.
There, since 1864, a gilded Madonna has shone like a beacon to mariners on storm-tossed seas, summoning the faithful and affirming the Christian identity of the city beneath.
Except that Marseille, after another generation or two, may well have a Muslim majority, which is why 15 years ago the city government approved a giant mosque on one of the western hilltops as a symbol of approbation and integration.