1800s

By the 1800s at the latest the Arcateenians had faster-than-light travel capabilities, including transporter systems and superluminal communications technology. (TW: Greeks Bearing Gifts, SJA: Invasion of the Bane)

Openings to the Yssgaroth's Universe were be found in 1800s in London, near Stonehenge and on the unnamed planet in the Althosian system. (NA: The Pit)