New York, Oct. 4 -- Lanterns, a piano, and a city holding its breath: inside the Brera courtyard farewell that distilled Armani's grammar of ease-and mapped the road ahead.

There are fashion shows you attend, and then there are rites. Giorgio Armani's last collection, presented in the cloistered courtyard of Milan's Pinacoteca di Brera, felt like both: a finale that doubled as a civic ceremony for a city and an industry that he helped define. Under the porticoes, with lanterns pricking the dusk and a live piano score drifting over stone, Milan offered its salute to the designer who made discipline look effortless and elegance feel like breathing.

The evening had been slated to mark fifty years of the house that bears his name. After the...