"The atrium was still elegant, peacock mosaic on the floor and Theseus overcoming the Minotaur on a wall."
-Poul and Karen Anderson, Roma Mater (London, 1989), p. 45.
If you read what I call Poul Anderson's Past in the order that I suggest, then the three novels set BC immediately precede the King of Ys Tetralogy co-written by Karen Anderson. Thus, a version of Theseus appears just two volumes before Roma Mater, in The Dancer From Atlantis.
On p. 50, Gratillonius reflects on Time the Hunter and thus echoes the title of a haunting story in Poul Anderson's Kith future history. Anderson's aliens, the Ythrians, refer to "God the Hunter" Who perhaps personifies Time the Hunter. Gratillonius' later references to the Roman general Marius echo the title of the opening installment of Anderson's Psychotechnic History and Marius drives back a barbarian invasion of Italy in The Golden Slave, the volume immediately preceding Roma Mater.
In these and many other ways, Poul Anderson's works display not only diversity but also unity.