The building burnt down on 12 February 1816. Six days after the fire, King Ferdinand IV (the son of King Charles) asked the architect Antonio Niccolini to build the theatre again. Nicolini used Medrano's designs but he made the stage bigger. The inside of the new Teatro di San Carlo was even more beautiful than the first one. The new theatre opened on 12 January 1817, with an opera by Simon Mayr, " (Partenope's Dream). Since then, only small changes were made to the building. It was damaged by bombs during World War II, but American and British soldiers soon repaired it.