Many Histories

Long though it is, Poul Anderson's History of Technic Civilization is dwarfed by the same author's complete works. However, the Technic History also connects with many of those works. First, it is one of Anderson's many hard sf fictional futures and is even one of several "future histories." Secondly, Nicholas van Rijn, Master Merchant Polesotechnic League, cameos in the fantasy short story, "House Rule."

Four novels and two short stories, including "House Rule," present a fictional multiverse that incorporates:

a universe like ours;
the Carolingian universe of Anderson's Three Hearts And Three Lions;
the Shakespearean universe of his A Midsummer Tempest;
the magical universe of his Operation Otherworld;
the inter-universal inn, the Old Phoenix;
Anderson's Technic History;
Heinlein's Future History;
therefore also Heinlein's multiverse but let's not go down that road;
EE Smith's Lensman universe;
Aztec gods;
Holmes and Watson;
Huckleberry Finn -

- but not Anderson's Time Patrol series which has a "one timeline-at-time" metaphysics - and, having referred to time travel, I expect soon to return to the time travel/alternative history novel that was interrupted by this digression back into the Technic History and related works.