If 50 percent or more of a zoning lot is located within a district to which the provisions of Sections 23-65, 24-54, 33-45 or 43-45 (Tower Regulations) apply, and the remaining portion of the zoning lot is within a district to which such provisions do not apply, any building or portion thereof which, in the aggregate, occupies not more than 40 percent or, on small lots, the percentage set forth in Sections 23-65, 24-54, 33-454 or 43-451 (Towers on small lots) of the lot area of the entire zoning lot (which building or portion thereof is hereinafter referred to as a tower) may penetrate any applicable established sky exposure plane, provided that such tower shall comply with the applicable setback requirements or restrictions on aggregate area that may be occupied within 50 feet of a narrow street or 40 feet of a wide street, as set forth in Sections 23-65, 24-54, 33-45 or 43-45.

If 50 percent or more of a zoning lot is located in a district in which the provisions of Sections 33-455 (Alternate regulations for towers on lots bounded by two or more streets), 33-456 (Alternate setback regulations on lots bounded by two or more streets) or 33-457 (Tower setbacks on narrow blocks) apply, and the remaining portion of the zoning lot is within a district in which such provisions do not apply, any building or any tower that occupies not more than the applicable percent of the lot area of a zoning lot as set forth in Section 33-455 or 33-456 and which complies with the applicable setback requirements as set forth in Sections 33-455, 33-456 or 33-457, may penetrate any applicable established sky exposure plane.

Subject to the requirements set forth hereinbefore and those specified in Sections 77-22 (Floor Area Ratio) and 77-23 (Open Space Ratio), such tower may be located anywhere on such zoning lot.