Multiverse

Poul Anderson's inter-universal inn, the Old Phoenix, is the setting for:

"House Rule"
"Losers' Night"
A Midsummer Tempest, xi THE TAPROOM OF THE OLD PHOENIX.
A Midsummer Tempest, xii LATER.
A MidsummerTempest, Epilogue THE TAPROOM OF THE OLD PHOENIX.

In A Midsummer Tempest, the inn is a meeting place for:

Prince Rupert from the Shakespearean universe of the same novel;

Holger Carlsen from the Carolingian universe of Anderson's Three Hearts And Three Lions;

Valeria Matuchek from the magical universe of Anderson's Operation Chaos and Operation Luna.

In "House Rule," the inn is a meeting place for:

Nicholas van Rijn from the hard sf universe of Anderson's Technic History;
Sancho Panza from Don Quixote;
Erik the Red, possibly from our universe.

Other guests from our universe or nearer ones include:

the first person narrator of the two short stories;
Leonardo da Vinci;
Albert Einstein;
Heloise and Abelard;
Francois Villon;
Winston Churchill;
an unnamed but identifiable Irish political leader.

Anderson wrote that he hoped to return to the Old Phoenix again...

The inn could have provided a framing sequence for a collection of new stories to display each of the different genres that Anderson wrote. Neil Gaiman used his Inn of the Worlds' End as a Chaucerian venue.

Today, I have read in Latin Caesar's and Tacitus' accounts of the Druids and their resistance to Roman rule.