At 370 metres, Passage du Caire in the 2ème arondissement is the longest of Paris’s passages couverts, and also one of the narrowest. It was opened in 1798 during Napoleon’s Egyptian campaign, and the name reflects the subsequent fad for all things Egyptian and Oriental. From 1840 onwards it was mainly occupied by printers and lithographers (which drove away the fashionable flâneurs) and thereafter by manufacturers of shop window dummies.
Being right at the centre of the Sentier quartier, it is nowadays taken up with fabric and garment wholesalers. Information from French wikipedia.
Le Passage du Caire is currently part of an “Opération Programmée d’Amélioration de l’Habitat” (Programme for Improvement of the Habitat) in the 2ème arrondissement, one of the objectives of which is to “mettre en valeur le patrimoine architectural, notamment celui des passages” (develop and enhance the architectural heritage, especially that of the passages).