On Block 1 or 2, as indicated on the District Plan in Appendix A of this Chapter, the maximum height of a building or other structure shall not exceed 275 feet above curb level, except that a penthouse may be located above such height, provided that such penthouse:

(1)        contains not more than four stories or 40 feet, whichever is less; and

(2)        the gross area of each story does not exceed 80 percent of the gross area of that story directly below it.

The underlying allowances for permitted obstructions above such maximum height limit shall apply.