 The original building contained ILLIAC I, one of the first supercomputers.In 1989, another addition added a third floor and enclosed the old building on three sides, and the building was re-addressed according to the location of its new main entrances near Springfield Avenue (the original building walls can still be seen from the inside).In 2004, the Computer Science department offices moved to the Siebel Center upon its completion, and most of the office space in DCL is now occupied by Technology Services at Illinois, the campus's central IT department, which had previously shared the building with Computer Science.