Controversial plans were unveiled Wednesday for a new basketball arena in Downtown Brooklyn that could be the new home of the New Jersey Nets.

“Forget the Dodgers” — the last major professional sports team to call the borough home — “Brooklyn’s future is the Nets,” said Borough President Marty Markowitz.

The 20,000-seat arena was designed by Frank Gehry, best known as the architect of the Guggenheim Museum in Bilbao, Spain. It would rise at the corner of Flatbush and Atlantic avenues, on top of rail yards for the Long Island Rail Road.

"The opportunity to build an arena in a very urban setting is very unique," said Gehry. "Most of them are built out in the fields where there's lots of parking around them. This has a different character."

“We are on the threshold of restoring Brooklyn to its rightful place on the national sports stage,” Markowitz said. “Brooklyn, as everyone knows, is a world-class city, and it deserves a world-class team playing in a world-class arena designed by a world-class architect.”

The plan, which also includes a housing complex and office and commercial space, is the idea of developer Bruce Ratner, who bid $$275 million to buy the Nets and move them to Brooklyn. The Nets’ owners are also considering lower offers that would move the team to Long Island or keep it in New Jersey.

"We are going to be successful at this," said Ratner. "We are going to get the Nets to Brooklyn, if it's the last thing that I do."

“We’re at the beginning of the process,” Mayor Michael Bloomberg said at the unveiling at Brooklyn Borough Hall. “We don’t have the Nets yet. You better get them,” he said, jokingly pointing a finger at Ratner.

The estimated $$2.5 billion bill for the development project would be footed by Ratner and other private investors, including the rapper Jay-Z, who was also on hand for Wednesday’s news conference.

"I'm a Brooklyn kid who's in love with Brooklyn and I'm just happy to bring something back to Brooklyn," said Jay Z.

The city has also thrown in its support.

"This will create construction jobs," said Bloomberg. "It will create housing, and it will create fun and excitement and reasons for people to come no only Brooklyn but to New York."

But critics say the plan will lead to congestion in the neighborhood. Opponents gathered outside Borough Hall to protest the plans Wednesday.

Although most of the development would be on top of the train yard, part of it calls for bulldozing a residential block in Prospect Heights.

“The community is already vital,” said Patti Kagan, one of the demonstrators. “And guess who revitalized it — all of the folks who have been living there for 20 and 30 years. It’s a very vibrant community. The way to destroy it is to bring in something like this, a monstrous project with all these skyscrapers — the ÎManhattanization’ of Brooklyn.”

The newly-elected city councilmember who represents the area, agrees.

"I do not like the fact that they're going to condemn an entire city block or a potion thereof and displace a number of businesses and individuals who live there," said Councilwoman Letitia James. "The fact is that stadiums have not shown to bring economic vitality to a community."

The project won't move forward, however, unless Brooklyn acquires the Nets. A decision is expected in the next couple of months.