Any use of land or building, any design of building, any location of building on the lot and any platted lot which lawfully existed on the effective date of this Zoning Ordinance may be continued even though such use, design or location does not conform to the regulations of this Zoning Ordinance for the district in which such use is located. However, no enlargement or expansion of such nonconforming building or use shall be made, except for two-family units and duplexes to which additions may be made subject to all the other review requirements of this Zoning Ordinance.