It is recognized that at the time of the adopting of this Zoning Code or any of its subsequent amendments, there shall exist lots, uses of land, structures, and uses of structures and land in combination which do not conform to this Zoning Code. While such conditions are permitted to continue, the purpose of this Zoning Code is to alleviate and eventually eliminate the undesirable consequences resulting from nonconforming lots, uses of land, structures, and uses of structures and land in combination which are detrimental to the purpose of this Zoning Code.