Thank you for the question. If you want to find a schedule and buy tickets for the Hungarian State Opera I recommend that you visit Jegymester. There you will find an overview of performances and you will also be able to order tickets online for any performance.
Notice that the Hungarian State Opera has a long summer break so from end of May/June until end of September there are no performances available in the State Opera. If you still want to visit the building there are guided tours every day at 15.00 and 16.00 in this period!
Enjoy and hope you find what you are looking for.
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