Volume 4 of Poul Anderson's collected works includes the off-cycle novel “The Million Year Shuttle.”

Rarely, very rarely—once a generation, once every few centuries—immortals are born among people. Their path lies through centuries of barbarism, across countries and continents. These are the heroes of the novel - the Phoenician Hanno, the Roman Rufus, Svoboda Volodarovna from Ancient Rus', Du Shan from the Han Empire...

A long life turns out to be not only a blessing, but also a curse - time washes away everything, both familiar faces and familiar ones era. But those who have walked their path to the end without breaking have the honor of leading people to the stars - and beyond.