The City of Palo Alto's Historic Inventory lists noteworthy examples of the work of important individual designers and architectural eras and traditions as well as structures whose background is associated with important events in the history of the city, state, or nation.The Inventory is organized under the following four Categories:
Category 1: An "Exceptional Building" of pre-eminent national or state importance. These buildings are meritorious works of the best architects, outstanding examples of a specific achitectural style, or illustrate stylistic development of architecture in the United States. These buildings have had either no exterior modifications or such minor ones that the overall appearance of the building is in its original character.
Category 2: A "Major Building" of regional importance. These buildings are meritorious works of the best architects, outstanding examples of an architectural style, or illustrate stylistic development of architecture in the state or region. A major building may have some exterior modifications, but the original character is retained.
Category 3 or 4: A "Contributing Building" which is a good local example of an architectural style and relates to the character of a neighborhood grouping in scale, materials, proportion or other factors. A contributing building may have had extensive or permanent changes made to the original design, such as inappropriate additions, extensive removal of achitectural details, or wooden facades resurfaced in asbestos or stucco.
