A nonconforming use or building shall be a building, structure or use legally existing at the effective date of this chapter, or any amendment thereto, or a building, structure or use planned and under construction in compliance with existing laws prior to the effective date of this chapter, or any amendment thereto, and completed within a one-year period after the effective date of this chapter, or amendment thereto, and which does not conform with the use regulations of the district in which located. A building, structure or use allowed by variance in a district where it is nonconforming with any regulations of this chapter shall also be considered a nonconforming use. (See also definitions in § 124-8.)