The person is narrating a stage play.
とくとご覧あれ ~ ! ここはどことも知れぬどこででもある国。勤勉質素を奨励するおもしろみのない王様が国を治めておりまし た。
The part that confuses me the most is "どことも知れぬ". As for the part that follows, I think it roughly means "a country that could be anywhere".
The word "どことも知れぬ" means "No one knows where" or something like that. "どこででもある" is "can be anywhere".
If I were to translate this, I would translate it to "This is a country of everywhere and nowhere". Does that make sense to you?