For Mr. Armani, a renowned perfectionist, no idea was too big and no detail too small. Armani/ Archivio is both an unprecedented undertaking and a priceless resource for students, historians, vintage dealers, collectors, and all lovers of great clothes. Enter the site, and do anything from browsing complete runway looks on a mannequin to digging deep into the brand’s studio photography, replete with key details and corresponding campaign imagery. It is a lush and immersive Armani experience. (Truly: Would we expect anything less?)

Above and beyond creating the site itself, Mr. Armani also hand-selected 18 archival looks, which are now on display at the Giorgio Armani flagships in New York and Los Angeles—and they are all available to purchase.

The 18 looks range from 1987 to 2016, with a special focus on evening wear. It’s all classic Armani, with the glamour quotient cranked all the way up to high, underscoring Mr. Armani’s decades-long love affair with Hollywood. Before celebrity stylists became the intermediaries between A-list actors and the brands that vie to dress them, those actors largely chose Armani for both public and private life, with pieces that reflected their own taste, personality, and mystique rather than a stylist’s calculated vision. Actors—Jodie Foster, Sophia Loren, Michelle Pfieffer, Julia Roberts, and Cate Blanchett, to name but a few—went to Armani for his sleek, glistening gowns, which projected understated luxury and personal confidence. Each appearance felt distinct and authentic, embodying the star’s individuality as much as the Armani aesthetic.

The archival evening dresses on display at the Los Angeles Giorgio Armani flagship feature a palette of beige and champagne pink, as if colored by the sepia-tinted celluloid fantasies of Mr. Armani’s youth. The fact that none of the looks are easily dated by sight alone speaks to another affinity that Mr. Armani shared with the allure of cinema itself: timelessness. Not only do the gowns showcase the designer’s close connection to LA; they also represent his journey from maverick sportswear designer to world-class couturier. As Mr. Armani’s profile grew and his design vocabulary expanded, his use of métiers d’art including embroidery and beading became increasingly more sophisticated, his Poiret-inspired escapist fantasies were tempered by realism and restraint, and his gowns became like contained canvases that wore like a second skin, or a cloud of air. Blending elements of ethnic motifs and textiles from around the world, he layered color, texture, thread, and embellishment to create an effect that was wholly contemporary and new.