Who was the architect of the opera house where Thaïs was first performed?
Thaïs (opera):  It was first performed at the Opéra Garnier in Paris on 16 March 1894, starring the American soprano Sibyl Sanderson, for whom Massenet had written the title role. Palais Garnier:  It was called the Salle des Capucines, because of its location on the Boulevard des Capucines in the 9th arrondissement of Paris, but soon became known as the Palais Garnier, in recognition of its opulence and its architect, Charles Garnier.
Charles Garnier