Unfortunatly the original theatre doesn't exist anymore. In fact, in the second half of the XVIII century it was so crumbling, that the Academy had to rebuild it.
The Academy - then renamed "Academy of Science, Literature and Arts" by the empress Maria Theresa from Austria - commissioned the Architect Antonio Galli Bibiena to reconstruct the theatre, exactly in the same place. The building of the new theatre - called "Bibiena" by the name of his constructor - begun 1766, and on the 3rd December 1769 it was inaugurated.
Few weeks after the inauguration, on the 16th January 1770, Mozart, who was only 13 years old, came to Mantua from Salzburg to play a concert. On that occasion, the young Mozart said that the "Bibiena Theatre" was the most beautiful theatre in the world.