Professional actors are one step closer to gaining a new address in Cambridge, as the parking lot wedged between Mt. Auburn Street and Mass. Ave. steadily morphs into a theater.

The recent completion of the steel-beamed shell marks a milestone in the construction of the 45,000 square foot Zero Arrow Street complex, which will soon house a 350-seat theater.

The site will also contain rehearsal rooms and office space for the Carr Foundation and other Cambridge non-profit organizations.

The entire project is expected to cost $18 million.

The Zero Arrow Street complex was designed by architect Guy Grassi, who also drew up the plans for the Market Theater’s former location on Winthrop Street.

“The new building is not only more spacious. It is also more contemporary,” said Grassi.

“The façade will be made entirely of glass, while the other building used mostly brick to create its more sedate Neo-Georgian style.”

Grassi said that even though the shell is already set, the design of the interior is still being debated among the different theater companies who will use the space.

“It’s difficult to say right now what the new theater will look like,” Grassi said. “Things are still up in the air, but over the next two or three months these designs should be finalized.”

The next step in the construction involves putting up windows and walls, and otherwise polishing off the building’s façade.

The building broke ground last September and is expected to wrap up this fall.

The project’s superintendent, Edward Corey of A. J. Martini Construction, said that, in addition to being aesthetically-pleasing, the new building will be functional, even employing an environmentally-friendly heating system which recirculates groundwater and reduces the use of fossil fuels.

The new theater is a welcome addition to the neighborhood according to Jinny Nathans, president of the Harvard Square Defense Fund, who has been an avid supporter of the project.

“The acquisition and sensitive development of Zero Arrow Street by the Carr Foundation is a happy resolution of a long and hard fought case by the Harvard Square Defense Fund and the neighbors,” Nathans said.

“The theater and foundation constitute a wonderful use of the site for the neighborhood, for Harvard Square and for the city of Cambridge,” she said.

The Carr Foundation was formedformed in 1999 by Gregory C. Carr, a Cambridge resident and 1986 graduate of the Kennedy School of Government. Its mission is to promote human rights education and the arts. It sponsored the Market Theater troupe which performed highly-acclaimed productions in a intimate 99-seat space at One Winthrop Square.

After an 18-month run, the Market Theater troupe vacated their old building, in order to make room for the restaurant Upstairs on the Square and to gain a more spacious venue on Arrow Street.  

In a press release, Carr said he hoped to retain the intimacy of the theater’s previous location, while accommodating larger audiences and productions.

“We will continue to take risks on new artists and edgy material,” Carr said.

—Staff writer Kimberly A. Kicenuik can be reached at kicenuik@fas.harvard.edu.