(a)        For the purposes of this Section, except in C5-3, C5-5, C6-6, C6-7 or C6-9 Districts, the basic maximum allowable floor area for a zoning lot occupied by a landmark shall be the maximum floor area allowed by the applicable district regulations on maximum floor area ratio or minimum required open space ratio and shall not include any additional floor area allowed for public plazas, arcades or any other form of bonus whether by right or special permit.

(b)        The maximum amount of floor area that may be transferred from any zoning lot occupied by a landmark building shall be computed in the following manner:

(1)        the maximum allowable floor area that could be built for buildings other than community facility buildings under existing district regulations on the same zoning lot if it were undeveloped;

(2)        less the total floor area of all buildings on the landmark lot;

(3)        the figure computed from paragraphs (a) and (b) of this Section, inclusive, shall be the maximum amount that may be transferred to any one or number of adjacent lots; and

(4)        unutilized floor area may be transferred from one or any number of zoning lots occupied by a landmark building to one or any number of zoning lots adjacent to the landmark lot so as to increase the basic maximum allowable floor area that may be utilized on such adjacent zoning lots. For each such adjacent zoning lot, the increase in floor area allowed under the provisions of this Section shall in no event exceed the basic maximum floor area allowable on such adjacent zoning lot by more than 20 percent.

(c)        When adjacent lots are located in C5-3, C5-5, C6-6, C6-7 or C6-9 Districts and are to be developed or enlarged with commercial buildings, the following conditions and limitations shall apply:

(1)        the maximum amount of floor area that may be transferred from any zoning lot occupied by a landmark building shall be the maximum floor area allowed by Section 33-12 for commercial buildings on said landmark zoning lot, as if it were undeveloped, less the total floor area of all existing buildings on the landmark zoning lot;

(2)        for each such adjacent zoning lot, the increase in floor area allowed by the transfer pursuant to this Section shall be over and above the maximum floor area allowed by the applicable district regulations; and

(3)        the City Planning Commission may require, where appropriate, that the design of the development or enlargement include provisions for public amenities such as, but not limited to, open public spaces, subsurface pedestrian passageways leading to public transportation facilities, public plazas and arcades.

(d)        In any and all districts, the transfer once completed shall irrevocably reduce the amount of floor area that can be utilized upon the lot occupied by a landmark by the amount of floor area transferred. In the event that the landmark’s designation is removed or if the landmark building is destroyed, or if for any reason the landmark building is enlarged or the landmark lot is redeveloped, the lot occupied by a landmark can only be developed or enlarged up to the amount of permitted floor area as reduced by the transfer.

(e)        As a condition of permitting such transfers of development rights, the Commission shall make the following findings:

(1)        that the permitted transfer of floor area or variations in the front height and setback regulations will not unduly increase the bulk of any development or enlargement, density of population or intensity of use in any block to the detriment of the occupants of buildings on the block or nearby blocks, and that any disadvantages to the surrounding area caused by reduced access of light and air will be more than offset by the advantages of the landmark's preservation to the local community and the City as a whole;

(2)        that the program for continuing maintenance will result in the preservation of the landmark; and

(3)        that in the case of landmark sites owned by the City, State or Federal Government, transfer of development rights shall be contingent upon provision by the applicant of a major improvement of the public pedestrian circulation or transportation system in the area.

The Commission shall give due consideration to the relationship between the landmark building and any buildings developed or enlarged on the adjacent lot regarding materials, design, scale and location of bulk.

The Commission may prescribe appropriate conditions and safeguards to minimize adverse effects on the character of the surrounding area.