Unfortunately when opening the file I forgot to select transparent background so I simply turned down the fill to 56% and started drawing the colours onto the underlying layer, taken from my colour palette, which gives this picture a bit of a washed out look.
This picture explains where the fresh air gets in as the Argians simply rely on the caves and tunnels to sort themselves out. These are just small crack in the surface that let air in, but not rain for example as that would likely flood the whole city. There is always some draft coming through and the stormy season can be quite rough underground, as your drying clothes might fly away if not secured properly.
The transport systems exists in stairs and mechanical lifts for goods which is difficult to handle by one person only but it can carry a great load. The stairs are present on any floor and represented by the diagonal lines going up and down. They are nice and broad and not too steep and some have even pretty decorations.
This picture shows the original colours I was using, without the fine lines. I just really like the look of it, as it is bright and happy and you can still see all the important patterns and what's going on.
