Regional Center Zoning- Highest Best Use: Mixed-Use Building, Office Building (may be Mixed-Use w/Office on one or more floors). Border of Holly Springs and Apex two of the fastest growing areas. Buildings may stand two to ten stories tall in the immediate center of the development, and the public spaces between buildings should be designed for active living, community gathering, and interesting street life. Residential units or office space may be found above storefronts.