Blue Cross Building, Boston, MA, 1957-1960


See also the architect’s proposed remodel and addition to this building prepared in 1986.
“We’ve made an effort to make the mechanical system into something more meaningful than just keeping you hot or keeping you cold or keeping you dehumidified, or whatever it is. For instance, in this building the support of course comes from the bottom. But the mechanical system is like a great octopus, coming from the top, and encircles the whole building. The hot air and the cold air and the returns are outside the columns, and then the horizontal branches are clearly shown. So that this becomes like a great vine encircling the whole building.”
Rudolph, Paul Marvin, 1918-1997, and John Peter, 1917-1998. John Peter Interviews Paul Rudolph [Transcript of Sound Recording]. Library of Congress, Washington, DC, 1959. 
"The reason this building is faced with precast concrete elements, Rudolph says, is that it stands on a masonry street in a masonry city, where a glass-and-metal curtain wall might look out of place. Moreover, Rudolph admits that he prefers buildings that respond to light and shade to buildings that are 'all reflection.' (Actually, the building façade is 50 per cent glass.) 
The reason the air-conditioning ducts are expressed on the face of the building is that, according to Rudolph, the mechanical equipment nowadays eats up some 40 per cent of building budget, and deserves to be expressed just as prominently as the structure. To the further question of why ducts and columns seem to be similarly expressed on the facade, Rudolph answers that, to him, they appear sufficiently different - the columns grow out of Y-shaped stilts, and the big return ducts are cut off at the third-floor level. He adds that what he and his associates tried to achieve was a rich, many-faceted building texture, and that the means are of secondary importance. 
Finally, Rudolph points out that the 'soft corners' are intended to 'carry the eye around the building,' which is freestanding."
"Boston Bucks a Trend." Architectural Forum 113 (December 1960): 64-69.