An ordinance of the Mayor and City Council is required to: add a structure and its appurtenant property to the Landmark List: Exteriors or the Landmark List: Public Interiors; or for a structure already on the Landmark List: Exteriors, to modify the boundaries of the appurtenant land or other property that is included in the Landmark designation. City Code, 1976/83, art. 1, §40(l)(3) 2000, Art. 6, §3-2(d) Ord. 67-939 Ord. 99-547 Ord. 07-550 Ord. 15-408