At the edges are high walls to keep the atmosphere in and protect the inhabitants from radiation, typically tens or hundreds of kilometres high.
The walls are typically tens or hundreds of kilometres high. At the edges are high walls to keep the atmosphere in and protect the inhabitants from radiation.
At the edges are high walls to keep the atmosphere in and protect the inhabitants from radiation. The walls are typically tens or hundreds of kilometres high.
At the edges are high walls to keep the atmosphere in and protect the inhabitants from radiation. The walls are typically tens or hundreds of kilometres high.