Beneath the lunar surface, a gigantic city reaching three thousand meters deep had taken shape.
Its main structure was unusual, with a hollow shaft running through its center from top to bottom.
The Residential Area, Industrial District, Storage District, and Transit Level spread out in concentric rings, making the whole city resemble a mushroom.
The head of the lunar project stood and began his report:
"The main structure of the Guanghan Palace Underground City is complete. It is designed to accommodate one million people, and overall completion currently stands at seventy-three percent."
"We adopted this structure because of the World Tree."
The image on the screen zoomed in.
At the center of the mushroom-shaped city, a World Tree that was not yet particularly tall had taken root.
At the very bottom of the central shaft, its crown grew upward through the hollow well, pale green points of light flowing slowly among its branches and leaves.
Elder Zhao looked at the tree and asked:
"How is the oxygen supply?"
The head of the ecology team answered immediately:
"A mature World Tree, combined with our own oxygen production capacity, will be enough to meet the basic needs of the city's entire population of one million."
"However, this World Tree is still growing. In the short term, we will continue to rely primarily on water electrolysis for oxygen, while the World Tree handles ecological regulation."
At this point, his tone grew noticeably more relaxed.
"The good news is that both lunar poles have ice resources."
"With nuclear fusion supplying energy, oxygen production is not a problem."
Lin Mo nodded.
The moon had no atmosphere, nor did it have the natural protection Blue Star enjoyed.
If they built a city on the surface, even entirely enclosed structures would have to contend with temperature differences,