Where did Mozart's Don Giovanni premiere?

Little short Mozart, just on five foot tall, composed what is probably the tallest Opera ever written, in 1787, the same year as Salieri's Axur, Cimarosa's I tre amanti and Kozeluh's Mose in Egitto. A composer called Gazzaniga also wrote a Don Giovanni the same year, earlier in fact, and most likely showed Mozart how not to write the opera.