This is not the building's entrance. It is a mural on the building at LaSalle and Division. Originally done in 1980 by artist Richard Haas and restored in 2005, it is titled "Homage to the Chicago School of Architecture".
It is quite the detailed mural - even including a shadow to continue the illusion that it is three dimensional.
It includes portraits of Frank Lloyd Wright, Daniel Burnham, Louis Sulivan, and John Root (see detail below), architects closely associated with the Chicago School of Architecture.