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Opened his first couturier in 1947 on Avenue Montaigne to be near the Hôtel Plaza Athénée and its international clientele—soon to be his. And just over a year ago, the beauty wing of the House of Dior moved into the famed hotel, fashioning a five-room showstopper boutique du beauté on the cave level. The brightly lit Dior Institut (it’s legally not a “spa” in Paris unless there’s mineral-spring source) has a befitting catwalk entrance: a life-size media monitor displays promenading Dior models, dressed in various collections, who virtually escort you in. Also tres dramatique are a suspended glass water-droplet over a decorative mosiac pool (a nod to "spas"), Louis XVI-style medallion chairs, and jewelbox-like quilted walls, which reinforce a cosseting feeling as well as the grey-mauve color scheme of the Dior Capture beauty range.

While most other beauty institutes in Paris completely lack a shopping and sampling area, Dior spotlights its high-tech skin-care products, which are featured in the high-performance facials. These involve a thorough exfoliation (with sapphire particles no less), lots of facial firming massage, and a slathering of the big-name anti-aging ingredients. You’ll pay dearly for the designer facial: The premier L’Or de Vie, with antioxidant grape extracts derived from Château d'Yquem, the famed chateau, costs close to dinner for two upstairs at Alain Ducasse (490 euros, 120 mins.).

A newer offering, the Dazzling Radiance (60 mins., 110 euros), is the menu’s sale-rack item. My skin looked naturally radiant afterward and walked around the city afterward with a French-woman's confidence. My only quibble: the facialist painted on the pull-off hydrating mask from chin to hairline, right over my eyes. And I feared for my lashes and brows. Next time I won’t go it alone: The Institut has a couples’ treatment room, one of just a few in Paris.