BOSTON (AP) – Harvard University plans to build a 500,000-square foot complex for stem cell research and other arts and science initiatives in Boston’s Allston Village.

The commitment is “the first big push” in Harvard’s Allston Initiative, Steven Hyman, Provost of the university, said Friday.

Boston Mayor Thomas Menino first announced the Harvard plans in his annual address to the Boston Municipal Research Bureau on Friday.

The 10-year initiative outlines plans for the Allston campus which includes Harvard Business School, athletic facilities and administrative buildings, across the Charles River from the university’s main campus in Cambridge.

Chris Gordon, head of the Harvard Allston Development Corporation said the complex is expected to incorporate environmentally conscious “green architecture,” and a campus feel, “definitely not high rises.”

Harvard has chosen a German architectural firm, Behnisch Architects, to design the complex. Several other cross-departmental science initiatives also will be housed at the site south of Western Avenue, east of the intersection at North Harvard and next to the offices of public radio and television broadcaster WGBH.

Menino noted the Harvard expansion as one of the ways Boston could make contributions to society and still benefit economically.

“Work with stem cells can save lives,” he said, “and we’ve got to be competitive.”

Groundbreaking for the new building is expected in 2007.

“Moving forward with this complex means planting a stake in the ground, from which we will advance this potentially life-saving science,” Douglas Melton, co-director of the Harvard Stem Cell Institute, said in a statement.

Harvard also plans to create an interim arts museum in Allston, while plans for a permanent arts and culture complex in Allston are refined.

The expansion into Allston is the first step in transforming 200 acres of Harvard-owned land in Allston.

The ultimate size of the new campus depends on planning that has just begun between a handful of different departments.

“This is a big first step,” Hyman said. “Ultimately this is a very long term plan. We may not be done building for many decades.”

Residents of the Allston community have mixed feelings about expansion, according to Tim McHale, member of the Allston Brighton Community Planning Initiative. The group formed in response to increasing development in the Allston and Brighton communities.

On the one hand, McHale said, the university’s expansion creates “an unbelievable opportunity” for economic growth. On the other hand, he said, the “Harvard Square of the Future” could boost the already high real estate prices, pushing out those who call Allston home.

Harvard is putting a lot of money into Allston, McHale said, “we as a community need to get smart as to what that means.”