The Gaillard Municipal Auditorium, Charleston's largest performance venue and an essential stage for local arts groups and Spoleto Festival USA, will undergo extensive renovations beginning as early as 2011 if enough money can be raised to pay the hefty price tag.

The project likely would cost more than $100 million, according to proposals submitted by David M. Schwarz Architects, a firm recognized for its work on civic and cultural projects. It would be spearheaded by the city and supported by Spoleto officials and others.

Martha Rivers Ingram, chairwoman of Spoleto's board, said a $20 million matching gift already has been committed.

The auditorium sits in a tax-increment financing district, according to city Chief Financial Officer Stephen Bedard. Theoretically, the city could raise funds by selling bonds against future tax revenues generated as a result of urban improvement.

Stressing the preliminary nature of the plans, Mayor Joe Riley said the city strongly supports the project.

"It will not be easy, but this city is a prominent center for the arts now, as it was 250 years ago, and we should have a building that is on par with the fine performing arts venues that exist in America today," he said. "It's clear that this is something we should seek to do."

Riley said the city has been considering a new concert hall for a while, and concluded that the current site of the Gaillard is the best place for it.

"We were already thinking of this when we received notification of a most extraordinary gift, an anonymous gift of $20 million," he said.

Since then, Riley has met with the architects in Washington and Charleston, and he has visited the Bass Performance Hall in Fort Worth, Texas, a Schwarz Architects building that opened in 1996.

Riley said the project could have far-reaching impact.

"Economically, this has a tremendous benefit to the community. You attract visiting performing arts (groups) to the community because they would like to come to the community. But if the venue has a great reputation then that has a draw, too."

Should the renovation proceed, the auditorium will keep its name, Riley said.

The Gaillard, at 77 Calhoun St., was built in 1968 for $6 million (equivalent to about $40 million today), and sparked controversy because of its impact on the surrounding black neighborhood.

Spoleto Festival General Director Nigel Redden said upgrades to city facilities are common and typically reflect the vitality of the community, not its failings.

"The mayor is good at restoring historic and civic buildings," Redden said.

Building improvement projects conducted under Riley's watch include the Confederate Museum building at the corner of Meeting and Market streets, City Hall, the Dock Street Theatre and Memminger Auditorium, all of which has added value to the city, Redden said.

"Theaters are the kind of public buildings that do change, and change often," he said. "It's not an indication of failure. This is an affirmation that the Gaillard is important."

The auditorium has long been the subject of conversation among musicians and audiences concerned about its acoustical deficiencies, and many have complained about its drab physical appearance.

David Greenberg, founder of Connecticut-based Creative Acoustics, which is consulting on the Gaillard renovation plan and has worked on other Charleston projects, said in a 2007 interview that the auditorium would benefit from a number of enhancements.

"The Gaillard was not conceived as a concert hall, but as a multiple-purpose room more aimed at popular culture and amplified events," Greenberg said. It provides "a monophonic experience" in which the sound exists "somewhere in front of (the audience). They are observing something rather than being part of something."

Ellen Dressler Moryl, the city's Cultural Affairs director, said the project could not be in better hands. Riley has long been an advocate for the arts, Redden has managed one of the most successful festivals in the world and Ingram's arts philanthropy and advocacy is notorious, Moryl said.

"This is certainly the dream team that can get the job done to the benefit of Charleston's arts community, local user groups and audiences," she said.

The plans include five main options. A preferred option appears to be an extensive reorganization of the hall, public amenities and exhibition space within the existing structure.

• Seating would be reduced from 2,700 to about 1,700.

• The fan-shape hall would be converted into a horseshoe shape, and the size and depth of the balcony reduced.

• The orchestra level would include two center aisles.

• The large balcony would be replaced with two or three smaller overhangs.

• The large stage would lose six feet, and modifications would be made to the pit and surrounding backstage areas.

• A second level would be added to the Exhibition Hall, approximately doubling its square footage to 30,000.

• The exterior could get a neo-classical makeover, echoing the College of Charleston's historic Randolph Hall.

The cost of renovations start at about $105 million and could reach $150 million, according to the plans.

Ingram said a good performance space is essential. "The hall changes the experience of the symphony." People who assumed they didn't like orchestra concerts were surprised to discover they were wrong, she said.

She said the renovation project would do more than help arts organizations. It's a project that should be done "in the name of community improvement."

College of Charleston President George Benson said he hopes the school will be part of the discussions. "This facility's close proximity to our campus presents tremendous potential for new partnerships between the city of Charleston and the college's academic programs in the performing arts," he said.

George Stevens, president and chief executive officer of the Coastal Community Foundation, an asset management nonprofit that works with charities and philanthropists, said his organization will follow the city's lead.

"No matter what the final budget, this will be the highest goal for a fundraising campaign for the arts in the history of the Lowcountry," he said.