A new $85 million city high school will be built on the current Royal Adelaide Hospital site if Labor is re-elected on March 15.
Premier Jay Weatherill said the 1000-student school, to specialise in health and sciences, would open on the prime North Terrace site at the start of the 2019 school year.
Earlier Sunday, the opposition said it would seek expressions of interest from the public sector to use the existing buildings for health and aged care services.
The Royal Adelaide Hospital (RAH) will vacate the site in 2016 and move to a new complex being built further along North Terrace.
The premier said Labor would ensure the new school partners with South Australia's world-leading scientific and medical research industries.
Education Minister Jennifer Rankine said many parents living in and around the CBD would like their children to attend a city school.
"The Liberals' plan is to construct a mega school with 2450 students - making it one of the biggest public schools in the nation," she said.
"A re-elected Labor Government will consult with the community and then build on land that we already own."
Slash Architects won a design competition for the site in December with a plan that includes a high school, art gallery, hotel, community centre and museum.
The premier said the master planning process will determine the arrangements for the whole site, including the best location for the school, expected to span 10,000 square meters.
