Recessed fenestration and special architectural expression lines in the street wall are required as follows:

(a)        Except as set forth in paragraph (b) of this Section, the aggregate width of all recesses in the street wall fronting upon Broadway shall be between 15 percent and 30 percent of the entire width of such street wall at any story between the ground floor and 85 feet above curb level.

(b)        In Block 1, as indicated on the District Plan in Appendix A of this Chapter, for any street wall fronting upon the south side of West 63rd Street and extending along Broadway and/or Columbus Avenue to a distance of not less than 50 percent of the block front, the aggregate width of all recesses in the street walls along each such street shall be between 15 percent and 30 percent of the entire width of each street wall at any story between the ground floor and 85 feet above curb level and shall be between 30 percent and 50 percent of the entire width of each street wall at any story above 85 feet above curb level.

(c)        In Block 2, as indicated on the District Plan, the requirement of street wall recesses in paragraph (b) of this Section shall also apply to a street wall fronting upon the north side of West 66th Street and extending along Broadway and/or Columbus Avenue to a distance of not less than 50 percent of the block front.

Such recesses shall be a minimum of one foot in depth and shall not exceed a depth of 10 feet. Below a height of 85 feet above curb level, no recesses deeper than one foot shall be permitted in a street wall within a distance of 10 feet from the intersection of any two street lines.

In addition, along the street lines of Broadway, West 63rd Street and West 66th Street within Blocks 1 and 2, the street wall shall provide, at a height of 20 feet above curb level, an architectural expression line consisting of a minimum six inch recess or projection, for a minimum height of one foot and maximum height of two feet.