Paolo Soleri drew cities the way an engineer draws a machine: one enormous section, cut open so every level reads at once — dwellings, farms, workshops, hundreds of tiny figures proving the thing is inhabited. Graphite and technical pen on drafting paper, printed by MIT Press as black line on white stock.

The ochre comes from what actually got built. Arcosanti's tilt-up panels are cast in silt from the Agua Fria riverbed, so the concrete carries the desert's own colour. Line does the arguing; hatch density does the shading; the earth tones are the material, not decoration.