The Pont des Arts, in Paris, is a steel-and-wood footbridge that connects Left Bank to Right—or, more important to its history and its name, connects the École des Beaux-Arts, where generations of French artists were told how to draw, to the Louvre, where generations went to find out how to look. It was, until relatively recently, a soulful and solitary passerelle, where one could stand for hours in winter, mostly alone, staring out at the view west toward the older, stone parapet of the Pont Royal and the Eiffel Tower, or east toward Notre-Dame and the sharp-jawed Île de la Cité. The view north, toward the Right Bank, remained, until the end of the twentieth century, interestingly mixed, with the newly cleaned Cour Carrée of the Louvre straight ahead and, just to the right, the shiplike prow of the Samaritaine department store, proudly flying a couple of pennants from its top.

In the past nine years, all that has changed. La Samaritaine, which for almost a century and a half represented the “Bonheur des Dames,” the “happiness of ladies” (a title that Zola used ironically, referring to the bourgeois pursuit of material goods in department stores), has closed. The store is emptied, mute and dark and flagless, its fourteen hundred employees gone, as the French luxury conglomerate L.V.M.H. struggles to turn it into a postmodern, glass-encased beacon meant for another kind of woman and another kind of happiness, and so finds itself pitted against preservationists who want neither postmodern glimmer nor luxury glitter—who want, in fact, the same damn happiness for the same damn women.

Meanwhile, the Pont des Arts groans beneath the weight of the “love locks” that have become a rashlike infestation on small Paris bridges in the past few years. Lovers buy cheap padlocks from lock sellers, scribble their initials on the lock, shackle the lock to the bridge’s railings, and then throw the key into the river. At first, there were a few, then there were a lot, and now they are everywhere, about three-quarters of a million in all, locks shackled to locks shackled to locks shackled to locks, every square inch of the bridge crowded with black initials, brass bodies. Earlier this year, some of the grillwork of the Pont des Arts collapsed under the weight of all that love. The city government has been slow to act, partly for the usual exasperating French bureaucratic reasons—before something can actually be done, it must be decided if it is the administrative responsibility of the Prefecture of Police, of the Hôtel de Ville, or, perhaps, of the Ministry of Culture—and partly out of a genuine bewilderment over how to constrain the passionate gestures of tourists on whose illusions of Paris as the best place to declare one’s love the city’s economy ever more depends.

Two American women, not long ago tourists themselves, have emerged to energize and unleash the popular passion of Paris against the love locks. When Americans visit the bridge now, what there is to see is not the modern and the antique but another opposition: in the distance, the collapse of the grand bourgeois mercantile civilization of Paris and, straight ahead, the excrescences of mass tourism that have replaced it as a central Parisian industry. The view from the footbridge now, in the city that the American women came to savor and stayed to help save, offers a tight knot of paradoxes about the history of Paris, the tempering of glass, and the shackles of love.

In the late nineteenth century, Parisian department stores, which began as catchall indoor marketplaces, with individual venders selling drygoods, interbred with the glass exhibition palaces of the period to produce a new building type and a new idea of luxury: all the world’s goods suspended on multiple floors under the natural light of a great, and usually decorated, glass ceiling. La Samaritaine—the name derives from a seventeenth-century fountain with a bas-relief of the Samaritan woman that used to stand nearby—began as one of these closed retail drygoods markets, colonizing, piece by piece, a miscellany of buildings between the Seine and the Rue de Rivoli; Printemps and the Galeries Lafayette emerged as rivals farther back on the grands boulevards. The stores gave an identity to the neighborhood and an idea of popular luxury to the world. La Samaritaine was, by general agreement, the most “popular” of the great stores, a sort of Macy’s-plus, if one can imagine Macy’s on the banks of the Seine with a view of a Gothic cathedral.

Then, at the beginning of this new century, the crisis in retailing that has struck the rest of the world struck Paris—the grands magasins had to do battle with what are called here grandes surfaces, the super-big-box retailers that, though kept by law largely to the periphery, are nonetheless good at drawing shoppers in for inexpensive furniture and appliances. Just as the Zola-era department store drove out of business all the small shops of the quartier—the Parisian shopping streets beloved of Americans are a much reduced version of the older kind, with only perishables surviving—so the grandes surfaces have been driving out the great department stores.

When L.V.M.H. (the name of the conglomerate, overseen by the tycoon Bernard Arnault, combines the initials of Louis Vuitton and Moët Hennessy, the suitcase maker and the champagne house) bought an interest in La Samaritaine, in 2001, it had already turned the Bon Marché, on the Left Bank, from a bourgeois store to a luxe one—from an Alexander’s to a Bergdorf’s. It faced a bigger project with La Samaritaine: to turn the familiar Seine-side building into a five-star hotel, with controlled access to the once famous roof terrace and restaurant. L.V.M.H. approached the Japanese architectural firm of Sanaa. The plan that Sanaa came up with, which also included retail space and low-income housing, was officially inspired by the building complex’s original architect, Frantz Jourdain. Conceiving the project in Art Nouveau style, he left intact the various façades of the buildings on the Rue de Rivoli that it was recycled from. The renovation, the company announced, was “an opportunity to complete Frantz Jourdain’s unfinished project to give La Samaritaine a single, immediately recognizable façade in the Rue de Rivoli.”

The most striking exterior feature of the new architectural model is a billowing, wavelike wall of translucent glass meant to unify the Rue de Rivoli side both by referring to the original verrière roof and by creating a single visual unit that pulls the façades together. This kind of oceanic glass front has become a signature, even a tic, of contemporary French architecture—including the many glass façades by Jean Nouvel and Christian de Portzamparc’s twisted crystal tower at L.V.M.H.’s U.S. headquarters, on Fifty-seventh Street in Manhattan. The glass façade suggests, in turn, the long French infatuation with glass walls—prismatic, waving, billowing, or bending—as the symbol and material of modernity or, in this case, postmodernity.

Beautiful though the Samaritaine façade promises to be, its critics think that it distracts from the reality that the L.V.M.H. plan, centered on a new hotel, would make the old department store one more luxury destination for Paris transients, rather than a regular retailer for Paris residents. This transformation increased Parisians’ natural suspicion of Arnault’s enterprise—L.V.M.H. having become, to its doubters, a kind of sinister luxury-goods octopus, a monopoly vender of French brands to ascending Asia. When preparatory work began on the Sanaa design, two years ago, preservationists sued. The first level of French magistrates temporarily revoked L.V.M.H.’s building permit, then L.V.M.H. appealed, and the case now rests with the Cour d’Appel, which is expected to rule in early December.