We end 2015 featuring a pair of venerable downtown buildings that offered visitors million dollar views during this year’s Open House Chicago, hosted by the Chicago Architecture Foundation.
Those two buildings, the Aon Center (at 200 East Randolph Street) and its next-door neighbor Prudential Plaza (at 130 East Randolph Street), have far different exterior styles. One thing they have in common is an excellent view of Millennium Park, Lake Michigan and on the upper floors, most of downtown Chicago.
Aon Center was designed by Perkins & Will and built in 1973. It is, at 82 stories, the third-tallest building in Chicago. Its exterior was originally clad in marble. In order to achieve that, however, the structure depleted an important Carrara marble quarry in Italy. It’s the same quarry used centuries before by Michelangelo.
That material posed another problem for the building. It was cut extremely thin, and couldn’t handle extreme temperatures. That required a complete overhaul in 1992, when the Carrara marble was replaced by thick slabs of North Carolina granite.
Prudential Plaza was built in 1955 from a design by Naess & Murphy. The exterior uses a much different material than Aon: limestone and aluminum.
It’s also the first building erected over the old Illinois Central Railroad yards. High atop the building is another Chicago architectural imprint: the Prudential Rock of Gibralter logo, designed by Alfonso Iannelli, a collaborator of Frank Lloyd Wright.