The Route of Ages is a space-time portal that can lead to nearly anywhere or when. It takes the shape of a cube within a cube (a four-dimensional cube, called a hypercube or tesseract). It is the place "where opposites cancel time".
It is this portal through which Trance Gemini takes the Andromeda Ascendant and her crew. When the Andromeda passed through the Route of Ages, she arrived on a planet of the Seefra System (a future version of Tarn-Vedra), where Dylan Hunt finds out that he is the last of the Paradines.
The Route of Ages brought a lot of strange spatial and temporal anomalies to the Seefra system in Season 5, like a possible-future version of Dylan Hunt, or vast amounts of solar radiation to reignite the legendary Methus Suns. The Route of Ages appears as a blue outline of a hypercube, spinning, changing, and morphing.
In the episode "Pride Before the Fall", the legendary Progenitor of all Nietzscheans Drago Museveni journeyed through the mythical Route of Ages in his time-traveling journey to obtain the DNA of Andromeda crewmember Beka Valentine. Thus, he brought about the existence of his race in its ultimate form, modifying the results of his father's (Paul Museveni) work on the basis of his dealings with Beka Valentine, Telemachus Rhade, and Dylan Hunt.
In the episode "The World Turns All Around Her", former crewman Tyr Anasazi traveled through the Route of Ages with the newly united Nietzschean Prides, as he sought a way to weaken the Spirit of the Abyss and destroy the Magog, the aggressive race which threatened all the inhabitants of the Known Worlds. He perished there, slain by Dylan Hunt and Telemachus Rhade, after he sought a way out via a bargain with the Spirit of the Abyss to trade Beka Valentine for himself.
In the episodes "The Heart of the Journey (Part 1)" and "The Heart of the Journey (Part 2)", it was revealed that the Spirit of the Abyss was located in the very center of the Route. From there, it controlled and guided the hordes of the Magog in their onslaught against the galaxies. The crew of the Andromeda used Trance Gemini's sun to ultimately destroy it. Once the deed was done, the Route of Ages turned into a slipstream portal, thereby reuniting the nearly mythical planet Tarn-Vedra, homeworld of the legendary Vedrans, with the space-faring inhabitants of the Known Worlds.