Forget what you know about Dudley Square.

That’s the message Boston officials are spreading today as the city begins construction of a $115 million office and retail complex that aims to redefine Roxbury’s long-struggling commercial core.

The project includes a striking new headquarters for the Boston School Department as well as public parks and community spaces for art exhibits and other events. Unlike at the city’s other municipal buildings, the plan includes several retail spaces that officials hope to fill with a mix of restaurants and shops.

“You’re going to see a rejuvenation of this whole area,’’ said Mayor Thomas M. Menino. “It’s going to help people in the neighborhood to stay put because there will be more jobs and economic opportunity.’’

The project, which is over a decade in the making, will preserve the prominent Baroque Revival facade of the Ferdinand building at the heart of the square, while also expanding the structure to create a more modern six-story office complex. The building will have green rooftops, at least one of which will be publicly accessible, and officials are weighing options for a special lighting effect on its upper floors.

The Boston Redevelopment Authority conducted an unusually broad search for architects, eventually settling on an international team - Sasaki Associates Inc. of Watertown and Mecanoo Architecten, based in the Netherlands.

The firms have designed a multitiered building that offers a different aesthetic on each of its sides. The front entrance opens to a sweeping public atrium that could host meetings and events, while the rear of the structure has additional retail shops and space for a public park next to the Dudley MBTA station.