A use, building or structure which shall be made nonconforming, as defined in subsection 28-2.2, at the time of passage of this chapter, or any applicable amendment thereto, may be continued except as otherwise set forth in this section.

The provision regarding nonconformity shall apply only to a use, building or structure legally established or erected, but not to any use established or building or structure erected in violation of law, regardless of the time of establishment or erection.