This section recognizes that many land uses, buildings, parking areas, lots, signs, non-accessory signs, and site improvements in the City do not conform with the requirements of this Zoning Code either because (a) they were established before the adoption of zoning, or (b) they were legal when established but have become nonconforming due to later zoning amendments. It is the purpose of this section to regulate these nonconformities and to allow for the continued existence, use, modification, and expansion of these uses, buildings, parking areas, lots, signs, and site improvements subject to the limitations set forth in this section.