ORLANDO, Fla. — In this most-visited city in the country, tens of millions of tourists spend their dollars every year in a swarm of theme parks that have made this area famous around the world. Now, Orlando is trying to show itself as a place far different than a land of fantasy.

An important part of Orlando’s emerging presence as a mature and innovative city is the 14-square-mile Lake Nona project, which is being built on land that only a decade ago was mostly pasture.

Once finished, the development, being built by Tavistock Development Company, will resemble a city in everything but name, with hospitals, hotels, office buildings, schools and colleges, recreational and sports training facilities, retail centers, entertainment spots and, ultimately, about 11,000 homes and more than 25,000 residents. More than 10 million square feet of construction has been completed at a cost of more than $3 billion.

“We didn’t want to pave over this project with a bunch of production housing — we wanted to do something greater,” James Zboril, president of the company, said over the summer in the project’s Laureate Park Village Center. Nearby, children splashed in a large pool and adults worked out in a state-of-the-art gym, facilities built for the residents.

Beyond the normal, profit-driven imperatives of brick-and-mortar projects, Lake Nona has an additional purpose — wellness — a notion that is intended to permeate virtually every aspect of the community, Mr. Zboril said.

The Lake Nona property was bought in 1996 by the British businessman Joseph C. Lewis, the founder of the Tavistock Group, the developer’s parent company. He later doubled the site’s size by buying adjacent parcels. If the entire 9,000-acre property — 40 percent of which will be left undeveloped — were laid overManhattan, it would stretch from the financial district north to 66th Street and, in parts, as far west as Jersey City.

Two of Lake Nona’s top goals, the developer says, were to entice institutions and commercial entities to build on the site and to encourage their employees to live there, sparing them from commutes and providing daily conveniences within easy reach. Tavistock — using enticements like grants and free plots of land, and aided by state and local government incentives — set about persuading major medical and research institutions to move to the site as part of a life-sciences cluster.

Now known as Medical City, its 650 acres are host to Nemours Children’s Hospital; the University of Central Florida Medical Center; the Sanford Burnham Prebys Medical Discovery Institute; the University of Florida Research and Academic Center; the GuideWell Innovation Center, a research, education and incubation hub; and a Veterans Affairs hospital, the first for the 400,000 veterans who live in the Orlando area.

About 13 percent of Lake Nona’s home buyers work at a Medical City institution, and 11 percent work elsewhere in the area. An additional 13 percent are employed at Orlando International Airport, which is northwest of the project and within sight of much of it, and 27 percent work from home. At-home workers benefit from a high-bandwidth infrastructure that delivers internet service at one gigabyte per second.

Mr. Zboril said that, in an effort to build a place that inspires and helps create good health, Tavistock invited Lake Nona residents — about 11,000 people so far — to consider themselves a “living laboratory” and participate in formal health studies run by on-site institutions over many years. In the shorter term, residents are offered free activities like bike races, tai chi and yoga. Trails in the area will eventually total 44 miles.

To encourage what they describe as “environmentally conscious” lifestyles, the developer is limiting the community’s use of nonrenewable resources like gasoline by installing electric vehicle chargers. The developer is also minimizing the project’s impact on the environment by applying “green” construction practices, reducing energy and water use and reducing waste.

“There’s not anything like this in all of North America,” said Mayor John Dyer of Orlando, who said the city had spent more than $80 million to build roads and other infrastructure in and around the development. “Lake Nona is a great expression of what Orlando is all about,” said Mr. Dyer, who is known as Buddy. “It wasn’t just a place where someone was going to build tract housing. It was a place that was going to be an economic engine for the area.”

He said the development was part of an effort to “rebrand” Orlando, including a marketing campaign with the slogan “You Don’t Know the Half of It,” aimed primarily at companies and entrepreneurs who may want to relocate to Floridabecause of tax incentives. The mayor and the city’s Economic Development Commission are promoting several projects they say will elevate Orlando’s standing as a world-class city.

Downtown, about 15 miles north of Lake Nona, a public-private partnership plans to build a 68-acre, mixed-use development called Creative Village, with office buildings, schools, shops, apartments, a hotel and a new campus of the University of Central Florida for more than 7,000 students.

Other plans downtown include a $155 million soccer stadium with at least 25,000 seats, while the Camping World Stadium, built in 1936 and used for professional football games and other events, is being renovated at a cost of $200 million. An auditorium called Steinmetz Hall is to be added to the Dr. Phillips Center for the Performing Arts, a $488 million structure that opened in 2014 and houses the Walt Disney Theater and the Alexis and Jim Pugh Theater.

Beyond Lake Nona and downtown, other developments abound. Near Kissimmee, about 12 miles southwest of Lake Nona, builders are at work on a $70 million campus called the Florida Advanced Manufacturing Research Center. The aim is to attract technology jobs.

“If we could end up with a jobs factory, everything else would take care of itself,” Rasesh Thakkar, the senior managing director of Tavistock Group, the developer’s parent company, said of Lake Nona.

As the prestige of the Lake Nona project has grown, more institutions are coming aboard. The United States Tennis Association, which has 700,000 members, is scheduled to open its national training center in the development’s Sports and Performance District in January. The 63-acre site will have more than 100 tennis courts of various surfaces, including red clay imported from Cremona, Italy.

Another tennis organization, the 15,000-member United States Professional Tennis Association, which certifies instructors, plans to move its headquarters to Lake Nona next year, after 25 years in Houston. The sports district will also house a 23-acre training facility for the Orlando City Soccer Club, which competes in Major League Soccer’s eastern conference.

The University of Central Florida was a major partner as Lake Nona began to take shape. In 2005, Mr. Thakkar contacted John C. Hitt, president of the university, who was looking for a place to build a medical school. The developer’s gift to the university of 50 acres and $12.5 million was persuasive.

“That made it an easy decision for me,” said Mr. Hitt, who arranged to buy an additional 25 acres for a college of nursing and, later, a teaching hospital, for which he is seeking a partner.

Mr. Hitt said it had been “a delight” to watch the evolution of the development.

“It’s really taken hold,” he said. “Even during the recession, which was a friend to no one, we managed to keep moving ahead. I’m confident that we’re building a first-rate medical campus out there.”