Redevelopers are aiming to send innocent citizens to jail as two architecture firms join forces to convert the 155-year-old Charles Street Jail in Boston, which has been vacant for the past 15 years, into a hotel expected to open next year.

Families of patients at neighboring Massachusetts General Hospital, as well as superstitious passersby who are drawn to the peculiar charm of an antique jail, will comprise a portion of the hotel’s customers, according to Peter Diana, vice president of Carpenter and Compay, one of site’s developers.

Although construction on the building began in May 2005, the plan to renovate the jail, which housed criminals awaiting trial from 1851 to 1991, was first conceived in 2000 when Massachusetts General Hospital, which owns the land, commissioned Carpenter and Company to lead the reconstruction. Carpenter and Company then hired Cambridge Seven Associates and Ann Beha Architects to draw up blueprints and oversee the preservation of the Boston historical landmark.

Diana said that nightly rates for the rooms have not yet been determined, but he added that his company’s aim is to provide accommodations on par with the Charles Hotel.

Pamela Hawks, principal of Ann Beha Associates, said her company has renovated various prominent sites within and around Boston, including the Mary Baker Eddy Library, the Massachusetts Historical Society and the lobby of Symphony Hall. Ann Beha Associates have already met with the Boston Landmarks Commission, the Massachusetts Landmark Commission and the National Park Service to explore the best ways to protect the jail.

“Finding a use that preserved the features of the jail and gave new life to it was terrific,” Hawks said.

Susan Park, president of the Boston Preservation Alliance, said her group aggressively lobbied to preserve the jail until it became an official landmark, and she said she is pleased with the effort to recycle the old building while still maintaining the jail’s important features.

“I think [the renovation] is looking great,” Park said. “Of course there are always compromises, but the large body of the jail is being preserved as well as some of the wings.”

Park said that some members of the Boston Preservation Alliance were concerned that large parts, if not all, of the jail would be defaced or destroyed, but he was said most of the jail would be preserved in its original form.

“Everything that is still standing is being preserved,” Diana said. “The rotunda, the south wing, the west wing and the original portion of the north wing that is still standing will be preserved.”

Park stressed the historical relevance of the jail, which was originally designed by influential mid-19th century architect Gridley Bryant who also designed Old City Hall.

“The jail was very modern for its time,” Park said. “It was very humane. Prisoners were housed in different pods and it was light and airy because of the many windows. It is a very important, innovative building.”

The total cost of construction will be roughly $65 million and the hotel will open for business in June 2007, according to Diana.