PORTLAND, Maine — A group of residents has launched a campaign opposing the wave of large-scale commercial development projects in Portland.

The group, Keep Portland Livable, is taking aim first at the proposed Midtown project in the Bayside neighborhood.

The Midtown project includes four 15-story towers with 675 market-rate apartments on 3.25 acres of former scrap yards along Somerset Street. Two parking garages and about 90,000 square feet of retail space would also be included in the complex.

But Keep Portland Livable believes the project doesn’t fit with the scale or the character of the city.

“The Midtown project is a concrete canyon that will destroy our uniqueness. It will alter Portland’s skyline, create long shadows and fierce winds, and it’s being created in part with [residents’] tax dollars,” said Peter Monro, co-founder of the group, who works in Bayside.

Co-founder Tim Paradis said, “We can’t sit idly by while the city approves huge development projects that are out of scale, out of character, and a plain bad deal for Portland.”

In April, the City Council approved zoning changes that would allow the Midtown towers to be built to a height of 165 feet, 40 feet higher than the previous limit. The project is now being reviewed by the Planning Board.

The formation of the group comes as the city undergoes a building boom perhaps unlike any since after the Great Fire of 1866.

Two new hotels are under construction downtown, a third is planned, and renovation of the former Eastland Park Hotel is nearly complete. A luxury condominium building is being built in the India Street neighborhood, and a second one is proposed. And development is beginning on the $105 million Thompson’s Point complex, which would include office space, a hotel, a parking garage, and a 3,500-seat arena.

Altogether, about half a billion dollars of development is in the works, according to Keep Portland Livable.

“The city of Portland is changing, and faster than we think [it should],” said Paradis. “None of us will recognize the home we all love if we don’t get involved.”