https://en.wikipedia.org/wiki/Royal_Swedish_Opera

The opera company was founded by King Gustav III and its first performance, Thetis and Phelée with Carl Stenborg and Elisabeth Olin, was given on 18 January 1773; this was the first native speaking opera performed in Sweden.

But the first opera house was not opened until 1782 and served for a century before being replaced at the end of the 19th century. Both houses are officially called the "Royal Opera", however the terms "The Gustavian Opera" and "The Oscarian Opera", or the "Old" and "New" Opera are used when distinction is needed.