Transport Tube station
Transport Tubes are a fast way to move around on the Mars of the late 19th century. Each of the four cities, Argyre, Elysium, Hellas and Olympus has a station of these tubes that would allow fast travel to the other cities.
In Martian Dreams the system could only be accessed after getting into Olympus and repairing the power grid. Initially, Argyre was not available thanks to Raxachk blocking off the city. Only after forcing the way into Argyre did it become available again.
Lore[]
While they seem to have been related to pneumatic tube technology, such as we find at modern drive-through bank windows, I am unclear as to their exact structure and design. A shame. They were quite efficient.
- from The Lost Notebooks of Nellie Bly (Worlds of Ultima: Martian Dreams)