When it comes to buildings that are already built or complete, It would be a hard choice between the Trump, Woolworth, Metlife, New York Life, Municipal, and Helmsey buildings in NYC. The Tribune Tower and Wrigley Bldg. in Chicago. City Hall in Philadelphia, Custom House Tower in Boston, Cathedral Of Learning in Pittsburgh, Terminal Tower in Cleveland, PNC Tower in Cincinnati, LeVeque Tower in Columbus, City Hall in L.A., Smith Tower in Seattle, the Tower Life Bldg. in San Antonio, Royal York Hotel in Toronto, & Regions Bank Bldg. in Mobile. It's too hard to decide. Maybe I would pick them all and make a totally new skyline.
Of course I would throw the Fisher Bldg., Book Tower, & The Wayne County Bldg. in Detroit in the new skyline.