On Monday evening, Councillor at-Large Michael Flaherty and the Boston Redevelopment Authority officials he was intent on grilling about Mayor Thomas Menino's plan to move City Hall to the South Boston waterfront were just about the only ones left in the City Council's chamber.

"This is the fifth floor?" quipped John Palmieri, head of the city's planning and development agency, after the hearing was over. "This feels like the basement."

The joke came after over three hours of testimony, mainly from Boston residents opposed to the plan. After BRA officials gave their opening statements and before they could take questions from the panel of city councillors, a parade of perturbed citizens lined up to have their say.

One woman from Back Bay said if the mayor doesn't like the appearance of the building's Brutalist architecture, he should hang potted plants outside of it. A Charlestown man said there was little support for the move and suggested it would be like moving Fenway Park, the home of the beloved Red Sox, to Milton.

Council President Maureen Feeney said the present location, on top of a public transportation hub with Government Center and both the State House and the JFK federal building nearby, is ideal. The building can be retrofitted, she stressed.

If the conversation is about moving City Hall, why not consider other locations along with the South Boston waterfront, she asked. "Why not Dorchester?" she said. "We could keep going."

Palmieri said the moving of City Hall was part of an overall redevelopment plan that included revitalizing Dudley Square. "We're just beginning to get a handle on the issues we're going to deal with," he said.

Other BRA officials said they had started discussions with other agencies, including the Massachusetts Bay Transportation Authority, to address any concerns about citizens being able to get out to Drydock 4, where City Hall would be sited.

"The mayor has never stated that his desire is to see this building demolished," Palmieri said.

Flaherty pressed for more community input, "before you get too far down the road."

"The time is now," he said. "Not six months from now, not a year from now. The public should be engaged."

Palmieri responded that they were still attempting to assemble some "baseline information" first, instead of going out to the public and simply asking, "What do you think?"

Some viewed the hearing as a political affair for Flaherty, who is widely seen as attempting a run for mayor next year. Menino is expected to run for a fifth term.

"This isn't what's driving Councillor Flaherty," said Janice Loux, president of UNITE HERE Local 26, a union that supports the move and brought out dozens of its members for the hearing. "It's a political football."

Flaherty believes that the relocation push has already gone too far.

"It's a bad idea for the city of Boston," he said, noting that the BRA has already spent $2 million, spoken with other agencies and was a "lot farther along down the road than most people think" on the plans.

Future City Council hearings are planned on the potential of retro-fitting City Hall, along with a panel of independent architects and planners.