It was rebuilt and reopened on 11 May 1946 , with a brilliant concert conducted by Arturo Toscanini , with a soprano solo by Renata Tebaldi . It was rebuilt and reopened on 11 May 1946 , with a memorable concert conducted by Arturo Toscaniniâ '' twice La Scala 's principal conductor and an associate of the composers Giuseppe Verdi and Giacomo Pucciniâ '' with a soprano solo by Renata Tebaldi , which created a sensation .