ome of the Commerce overlays are slightly different than those described above.

Tax Income is similar to the overlays for other building types. Selecting this display shows your Senate building and forums, plus all of the tax collectors walking their routes. The column heights show how much money each housing lot has paid in taxes so far this year.

The Market overlay is also similar to those for other building types; it shows the locations of your markets, market workers walking their routes, and columns indicating level of market access for every housing unit.

The Desirability overlay looks quite different from other overlays. It rates each map square's overall attractiveness to anyone considering living there. Cooler colors, like blue and green, are raised slightly above ground level, and indicate highly desirable areas ; warm colors like orange and red are sunken below ground level, and indicate undesirable property. You want to build your most valuable housing in the most desirable areas, but be careful: If you start razing other buildings to make way for housing, you will change the desirability calculations.

The Labor overlay looks just like a “normal” overlay, but it's different in one important way: Most overlays show housing's access to other types of buildings, but the Labor overlay shows other buildings' access to housing. The columns in this display show how successful a building is at finding the laborers it needs to function at its fullest capacity. Buildings with short columns need either some housing built nearer to them, or a more direct road to some existing housing. If your city experiences a time of labor shortage, buildings with the worst access to labor are the first to lose their workforce.