Dueling centers chronicling the history of the mob are planned for Las Vegas, and it seems almost certain that someone is going to get hurt. Well, feelings anyway.

“I am not the least bit worried about them,” Mayor Oscar B. Goodman said of the potential competition to the Las Vegas Museum of Organized Crime and Law Enforcement, a city-sponsored project he has championed for years. That museum is set to open next March in the old downtown federal courthouse, the site of the 1950 mob hearings led by Senator Estes Kefauver of Tennessee.

“They are no competition because we are the real thing,” said Mr. Goodman, a former defense lawyer for reputed Mafia figures. “Forget about it.”

But the rival, which involves the daughter of the famed Chicago mob boss Sam Giancana, is promising a collection of mob memorabilia in the Tropicana casino on the Las Vegas Strip.

“Our experience will be very different from theirs,” said Carolyn Farkas, the spokeswoman for the museum, the Las Vegas Mob Experience. “Theirs is more a law enforcement accounting; for us it is more a personal view.”

The idea for the Las Vegas Museum of Organized Crime and Law Enforcement was seeded when the city bought the 1933 federal courthouse and post office from the federal government for $1 in 2002, with the strict understanding that the building — one of the oldest in Southern Nevada — be used for cultural purposes.

For much of the middle of last century, organized crime ruled the Strip, developing and managing an array of casinos, skimming their way to success. Federal prosecutors put an end to their reign in the 1980s. The city determined its historical relationship to organized crime — and the role the courthouse played in it — made the site a perfect fit. “It came from the soil of this building,” said Nancy Deaner, the city’s cultural affairs manager.

The building is being meticulously restored, down to the original coffered ceiling and crown moldings hidden for years and the original mustard, oxblood and royal blue colors long ago washed in white.

The $42 million project has been financed through a series of state, federal and local grants, and the work has progressed a bit glacially as money has trickled in.

The project, once listed as one that could stimulate this city’s embattled economy, was attacked by Senator Mitch McConnell, the Republican leader, when city officials suggested that it might qualify for federal stimulus money.

“That got blown out of proportion with morons in Washington shooting off their mouths,” said Mr. Goodman, whose office chair resembles a throne. He said he tried his first case in the court building.

The museum will have three stories and nearly 17,000 square feet of exhibits, including an interactive courtroom in which visitors can get finger printed. It will also include the brick wall from the St. Valentine's Day Massacre (it was removed brick by brick and put in storage but will be constructed, bullet marks and all, Ms. Deaner said), roughly 700 objects and extensive exhibits on law enforcement efforts against the Mafia.

The museum is dear to Mr. Goodman’s efforts to revitalize the downtown area of Las Vegas, which for years has been the dirty ashtray to the Strip’s gilded cup.

“This story is so rich, our efforts to tell it are hard to do in a museum this size,” said Dennis Barrie, the creative director of the museum, who curated the collections at the International Spy Museum in Washington and at the Rock and Roll Hall of Fame and Museum in Cleveland.

At the same time, Eagle Group Holdings — working with Antoinette McConnell, the 74-year-old daughter of Mr. Giancana — is looking to open the Las Vegas Mob Experience at the end of the year.

While executives from the Mob Experience declined to identify the planned site, a document provided by someone involved in the transaction who was not authorized to speak before a planned announcement of the deal next month shows an agreement with the Tropicana Las Vegas, which is undergoing a $165 million renovation.

The Mob Experience would include theme park-style exhibits, including one called “Final Fate” in which a visitor “gets made or gets whacked,” according to the description.

The Tropicana, one of the oldest properties on the Strip, had fallen on hard times over the years but was recently sold and is now co-owned and run by Alex Yemenidjian, a former chief executive of MGM Studios. Rather than demolishing the original structure, as has happened with other older hotels, the new owners are restoring it.

Mrs. McConnell, who splits her time between Las Vegas and Chicago, said in a telephone interview that such an exhibit had been “a dream of mine” for years and that it would offer “the greatest thing you have ever experienced.”

Mrs. McConnell, whose late husband was a lawyer who represented organized crime figures, added: “The Mafia is something that people can’t get enough of. For some people it is like an addiction.”

While Mrs. McConnell and Mr. Goodman could go head-to-head on hyperbolic enthusiasm for personal projects, Mr. Goodman says the sheer force of his gorgeous building, an esteemed staff and the power of his bully pulpit alone will make his museum the most talked about in town.

“My whole life has been competitive,” he said. “And I don’t lose.”