The Health Services Union sold the three adjoining properties, after it bought new offices in South Melbourne in February.
The buildings include a 1120-square-metre, three-level office building with a short-term lease to the union, another leased 1400-sq-m three-level office building, and a development site that agents say has the potential to be developed into an eight-level building.
An RMIT spokesman said the university would use the union-occupied building as administration offices, and might develop the vacant site later for teaching or administration purposes.
Killen Thomas director Martin Shembrey said RMIT competed with developers for the city-fringe site.
"There are virtually no development sites left in the south Carlton precinct, and this has contributed to high land values of up to $6000 per square metre, which I believe is a record for the area."
RMIT had planned to develop a $100 million mixed-use education, retail and student accommodation project on the former CUB site it paid $25 million for in 1998. Instead the site was sold to Grocon in December for about $39 million after ANZ Bank, which had considered the site for its new headquarters, announced it would move to Docklands.
? Developer R.Corporation said it would pay $7.06 million for an 8252-sq-m development site in Buncle Street, North Melbourne, which it plans to develop into low-cost housing.
R.Corporation chief executive Andrew Rettig said the company would lodge plans to develop the site immediately and hoped to start building in 2008.
"R.Corporation is keen to be able to offer low and middle-income Australians access to quality housing in convenient locations."