"A Tragedy of Errors" has an elaborate four-stage beginning.
(i) The italicized passage about the King of England and Christopher Wren in ancient times.
(ii) The omniscient or later narrator discussing the myth of Roan Tom.
(iii) Tom himself addressing us from a hypothetical Valhalla well supplied with Earth-grown tobacco. He begins a first person narration which, however, is soon discontinued.
(iv) A third person in media res beginning:
"The image in the viewscreens flickered so badly that Tom donned armor and went out for a direct look at the system he had entered."
-Poul Anderson, Flandry's Legacy (New York, 2012), p. 459.
(i) -(iii) make this story a good opener for a Post-Imperial Age volume. The mysterious narrator is this Age's equivalent of Hloch. The History of Technic Civilization has three parts:
the Extended Earth Book of Stormgate;
the Flandry period;
the post-Imperial Age.
All three sections are good fictitious history.