Architect John Massengale has called Savannah's city plan "the most intelligent grid in America, perhaps the world", and Edmund Bacon wrote that "it remains as one of the finest diagrams for city organization and growth in existence." The American Society of Civil Engineers has honored Oglethorpe's plan for Savannah as a National Historic Civil Engineering Landmark, and in 1994 the plan was nominated for inclusion in the UNESCO World Heritage List. The squares are a major point of interest for millions of tourists visiting Savannah each year, and they have been credited with stabilizing once-deteriorating neighborhoods and revitalizing Savannah's downtown commercial district.