What is the name of the opera house built by Wagner to stage his operas?

The Bayreuth Festspielhaus is the opera house specifically built by Richard Wagner to stage his operas. Wagner's vision for this theater was to create a space that would allow for his innovative approaches to opera, including enhancements in acoustics, staging, and the audience experience. He sought to separate the experience of opera from that of conventional theaters, emphasizing the total work of art (Gesamtkunstwerk) concept which he pioneered.

The unique architectural features of the Bayreuth Festspielhaus, such as its orchestra pit which is hidden from view, were designed to create a more immersive experience for the audience, allowing them to focus solely on the performance. This was a radical departure from traditional opera houses, making it a significant landmark in the history of opera.

The other venues mentioned, while significant in their own right, do not have the same connection to Wagner or his specific intentions for staging his works. La Scala, the Vienna State Opera, and The Royal Opera House are renowned opera houses with their own rich histories, but they were not designed with Wagner's artistic vision in mind.