The Traditional Neighborhood Design District is intended to promote a mix of small-scale retail, service, professional office and residential uses which serve the day-to-day needs of the residents of the surrounding neighborhoods. This district shall accomplish and continue a sense of community, providing a walkable, pedestrian environment and encouraging a mixture of uses and mixed-use structures, including residential uses on the upper floors of nonresidential establishments. Design regulations are included that encourage compatible building arrangements, bulk, form, character and landscaping to establish a livable, harmonious and diverse environment. The preservation of existing structures that possess significant historic or other essential elements that contribute to the character of the district shall be strongly encouraged.