<Tr> <Th> Structural engineer </Th> <Td> Naess & Murphy </Td> </Tr> <Tr> <Th> Main contractor </Th> <Td> George A. Fuller Co . </Td> </Tr> <P> One Prudential Plaza (formerly known as the Prudential Building) is a 41 - story structure in Chicago completed in 1955 as the headquarters for Prudential's Mid-America company . It was the first skyscraper built in Chicago since the Great Depression of the 1930s and the Second World war . The plaza, including a second building erected later, is owned by BentleyForbes and a consortium of New York investors, since the Great Recession of the early 21st century . </P> <P> The structure was significant as the first new downtown skyscraper constructed in Chicago since the Field Building, 21 years earlier and it was built on air rights over the Illinois Central railroad . It was the last building ever connected to the Chicago Tunnel Company's tunnel network . </P>

When was the prudential building in chicago built