The following building materials, and none others, shall be allowed in the construction of the exterior walls of a building that is visible from any public right-of-way in an OP-1 Office Park-1 Zoned District in the City: (a) brick; (b) brick veneer; (c) natural stone; (d) marble; (e) granite; (f) glass; and, (g) such other building materials as shall be:  (i) authorized and approved by the BOCA National Building Code in effect at the time of reference; and, (ii) may be authorized by the City Council, with he advice and recommendation of the City's Building Commissioner and/or the City's Architectural Review Committee.  The design materials shall be used in such a way as to blend with the scale, color, and traditional architectural character of the district.