The Widett Circle area of South Boston east of the Southeast Expressway is organizers’ top choice for a temporary 70,000-seat Olympic stadium.

Sites from Foxborough to Lowell would be used to host Olympic venues if Boston gets the nod as host city for the 2024 Olympic summer games, according to materials released Wednesday by the Boston 2024 committee.

The most intensive use would involve the Widett Circle area of South Boston east of the Southeast Expressway, which is organizers’ top choice for a temporary 70,000-seat Olympic stadium. The area includes a tow lot and public works yard owned by the city of Boston as well as a wholesale produce cooperative that supplies local restaurants and supermarkets.

Another cluster of events would be held on both sides of the Charles River in Allston and Cambridge, while South Boston would see intense activity including events held at Castle Island, the Boston Convention and Exhibition Center and along Fort Point Channel and the waterfront. The athletes’ village would be built at Columbia Point in Dorchester.

The dozens of properties that would be used for events include privately-owned parcels that organizers would acquire through negotiations or potential eminent domain takings, as well as those used through partnerships with local colleges.

According to the bid, 18 of the venues would be existing facilities or would remain in place for post-games “legacy use.” If it wins the approval of the International Olympic Committee, Boston would also host the Paralympics. The IOC is scheduled to decide in 2017.

The blueprint for what organizers say would be the “most walkable” Olympic games in the modern era hinges upon the completion of approximately $5 billion in transportation projects, some of which are already in the planning stages.

Those projects, according to organizers, include:

• The $1-billion expansion of South Station, which is tied to the relocation of the adjacent U.S. Postal Annex facility;
• The $1.6-billion Green Line extension to Somerville and Medford and the south Coast commuter rail extension to Fall River and New Bedford;
• Some $3.5 billion in overall improvements to transit systems in the region;
• Enhanced rail capacities between Worcester and the Boston waterfront costing $3.5 billion;
• The new Massachusetts Turnpike interchange in Allston for $160 million;
• More bike lanes and programs for $145 million;
• Dredging of Boston Harbor to accommodate larger cruise ships and container vessels.

Organizers estimate the operating costs of the games at $4.7 billion. They say the costs would be borne through private sponsorships and broadcast rights.

Not included in the materials released Wednesday were cost estimates for land acquisitions.

Daniel O’Connell, president of Boston 2024, said officials held back from releasing “specific financial items” on the estimated costs of procuring land or construction because they do not want to give away a bargaining advantage.

The bid that went to the USOC estimates workforce costs at $600 million, technology at $600 million, games services at $500 million and other costs at $500 million.

O’Connell said he believes the federal government will cover security costs as it does for other major events, and the bid said security and transportation are not included in the cost estimate.

The documents identify Somerville as a host site for a cycling velodrome and BMX track in the Assembly Square section, which is undergoing a multi-billion-dollar redevelopment.

In response to an inquiry, Somerville Mayor Joseph Curtatone released a statement Wednesday saying that the Olympic planning effort needs a broad community-based approach to ensure it brings long-term improvements to the region instead of a “three-week party and a legacy of abandoned structures.

“Planning for the Olympics must dovetail with community-building initiatives, and simply identifying locations for venues like a velodrome, which brings no long-term benefits to the community, won’t cut it,” the statement said. “I remain a willing, constructive partner to make the Boston Olympics a reality—as long as we can adhere to that community-based regional approach that focuses on the long-term needs of Greater Boston.”

The release of the documents this week and the first public presentation Wednesday night take place amid a spirited debate about whether the Olympics would bring broad benefits to the region or primarily benefit a small group of private business interests.

Opponents have indicated they will seek a statewide ballot referendum to gauge public sentiment. Evan Falchuk, chair of the United Independent Party in Massachusetts, said Wednesday that organizers have to prove the games would make financial sense and not require taxpayer subsidies.

“Should this fail to be the case, it will be clear that a voter referendum on the Olympics will be the only way to hold the ‘Power Elite’ behind this veiled process accountable to every taxpayer in Massachusetts,” Falchuk said in a statement.

A MassINC Polling Group survey found voters in the Boston region support hosting the games by a 51-33 margin. No Boston Olympics, a group mobilized against the idea, distributed talking points Wednesday that include support for a referendum and an “independent body of economists and experts” to weigh the proposal.

O’Connell dodged questions on a potential referendum, saying he would need to know the particulars, and did not say Olympics backers would drop the cause if voters rejected it in a referendum.

Meanwhile, House Speaker Robert DeLeo said Wednesday he wants to see 2024 Summer Olympics venues around the state not just in the greater Boston area.

Organizers should look to Springfield, Worcester, the South Coast and the Berkshires for venues, DeLeo (D-Winthrop) said Wednesday, adding, “I’d like to see the rest of the state share in some of the activities.”

In addition to the location of venues, DeLeo said paying for the Olympics is an issue he’s concerned about.

Asked if he backed a potential referendum on the Olympics in Boston, DeLeo said, “Right now I’d like to see if I can get answers to some of the questions which I just raised before I would be able to answer that. I feel that we’re sort of caught up in the frenzy and excitement of being chosen as the city.”

Material from Statehouse News Service contributed to this report.