New York Consolidated Laws, Public Buildings Law - PBB § 141. Display of foreign flags on public buildings

It shall not be lawful to display the flag or emblem of any foreign country upon any state, county or municipal building;  provided, however, that whenever any foreigner shall become the guest of the United States, the state or any city, upon public proclamation by the governor or mayor of such city, the flag of the country of which such public guest shall be a citizen may be displayed upon such public buildings.