Simplify the following text for a Grade 9 native English-speaking person.
Original: The reconstruction of the building was supervised by architect Carl Ferdinand Langhans , and the KÃ nigliches Opernhaus ( Royal Opera House ) was inaugurated the following autumn by a performance of Meyerbeer 's Ein Feldlager in Schlesien .
Simplified: It was called KÃ nigliches Opernhaus ( Royal Opera House ) , and it opened with a performance of Meyerbeer 's Ein Feldlager in Schlesien .