High-rise Loop office buildings. Also covers downtown stores, entertainment, and civic buildings. Allows residential buildings.
| Zoning Ordinance reference | 
            ยง 17-4-0102 View the Chicago Zoning Ordinance  | 
        
| Floor area ratio | 12 | 
| Maximum building height | None, but buildings taller than city's "building height thresholds" require Planned Development review. | 
| Lot area per unit (density) | 115 sq ft/dwelling unit, 75 sq ft/efficiency unit, 60 sq ft/SRO unit | 
| Minimum lot area | |
| On-site open space | All buildings with people living in them must have at least 36 sq ft of on-site open space per dwelling unit. (See 17-4-0410-A) | 
| Front yard | None | 
| Side | None | 
| Back yard | None |