The federal government's chief public health agency is preparing to open a rebuilt $1.5 billion campus here, one that reflects the contradictions of a nation worried about terrorism, global calamity and death while committed to personal happiness, healthy lifestyles and environmental responsibility.

Scientists at the Centers for Disease Control and Prevention will soon have the capacity to do five times as many experiments on smallpox virus, Ebola and other high-risk pathogens as they can now. Their laboratories are supposed to be relatively impervious to truck bombs, and it should be very difficult for strangers to get anywhere near them. Their bosses will track disasters and epidemics from a futuristic command center worthy of Hollywood's most apocalyptic scripts.

At the same time, the facility was designed to be prettier and more relaxing. There will be fewer lonely cubicles. The architecture will encourage researchers to engage in the sort of casual conversation that can spawn new ideas. Many will be able to look up from computer screens and gaze on a giant Japanese garden where captured rainwater ceaselessly flows down an exquisitely planted slope.

"We finally have world-class space for world-class people," Julie L. Gerberding, the CDC's director, said during a tour last week of the project's first phase.

She said that although many of the improvements are ones that "should have been done 25 years ago," the overall transformation "is a metaphor for a lot of changes going on in CDC."

The plans for the agency's reconstruction go back more than a decade, but they are heavily colored by recent events, said William H. Gimson, the CDC's chief operating officer. "This agency has completely changed since 9/11. The stakes are much higher, and failure is not an option," he said.

The CDC is descended from a World War II-era government program called "Malaria Control in War Areas." In 1946, it became the "Communicable Disease Center," with a task of tracking and controlling many infectious illnesses. Its budget was $10 million, and it had just under 400 employees. Even 20 years ago, the agency had a budget of only $400 million.

This year, the CDC's congressional appropriation is $7.7 billion (with some of the money going to build a drug and vaccine stockpile). It has more than 9,000 employees, with about 6,000 in the Atlanta area. In addition to offices in many states, the agency has several specialty laboratories across the country, such as the one in Fort Collins, Colo., that studies West Nile virus, tularemia, plague and other "vector-borne" diseases carried by animals or insects.

The CDC has two campuses here. The main one is next door to Emory University; a somewhat larger one is in suburban Chamblee, Ga. About 70 percent of the Atlanta-based employees, however, are in neither place. They are in about 35 rented offices scattered across the city like a load of buckshot.

The new construction will let the agency give up all but one of the rented sites and move nearly all employees to the campuses. That will provide them, and their scientific work, with greater security. It will also offer more opportunities for intellectual cooperation and cross-fertilization, Gerberding said.

There is little debate that many of the buildings on the campus are obsolete and needed to be replaced. Most of them date from the 1950s and 1960s; the main campus looks like a cluster of suburban high schools. Contemporary laboratories require much more service space for duct work, wiring and storage than they did 40 years ago, which means many of the existing buildings have been retrofitted several times.

The new buildings also reflect the evolution of the CDC's mission.

The most obvious evidence of that is the new $214 million Emerging Infectious Diseases Laboratory. It contains four "biosafety level 4" (BSL-4) suites, where researchers wearing spacesuits can work on the highest-risk germs, such as smallpox and hemorrhagic fever viruses, including Marburg, Lassa and Ebola. The CDC now has only two BSL-4 labs, and because of their design, all people using them have to work on the same microbe. A logjam of planned research dating back years will begin to break up.

Among the tasks that will get greater attention are the testing of antiviral drugs against smallpox and the search for the natural reservoir of Ebola virus -- the place where the microbe hides between outbreaks.

Fewer than 20 people on the campus are certified to work in BSL-4 conditions, where scientists work in pairs under constant video surveillance, the air-lock doors open only after those seeking entry are scanned with secret "biometric" sensors, and every drop of anything that lands on the floor is treated as a high-risk spill. A new group of researchers has begun arduous training in anticipation of the labs "going hot" in November, Gerberding said.

Dozens of new labs suitable for work on less hazardous bugs will also open this fall, and many more in the next few years. Ultimately, all of the CDC's laboratories will be set back from the surrounding roads and clustered in the campus's core, where no public traffic is allowed.

Other new structures include a command center where data from around the world and in every possible form can be gathered and displayed. The CDC has been in emergency operations mode at one level or another 21 times since Sept. 11, 2001, for events such as the anthrax spore letters, the outbreak of severe acute respiratory syndrome (SARS), vaccine shortages, the spread of West Nile virus and the South Asian tsunami. A new broadcast center will allow the agency to communicate with public health officers across the country -- and the public -- by television, closed-circuit video and webcast.

A $123 million environmental health laboratory -- for research on everything from water pollution to vitamins -- is about to open at the Chamblee campus.

The architects and engineers hope the huge refurbishment makes a statement about the agency's values even as it solves practical problems.

The core of the main campus is a sloping "greenscape" with a stream running over and around artificial rocks. Rainwater is collected and sent down the stream to a pond, where it is pumped back up to the top of the slope and sent down again. The system is the source of water for all of the campus's sprinklers.

"Check out the stairwells," Gerberding said as she stood on a limestone bridge over the chasm and pointed at the window-clad facade of one of the new buildings. "They're lit. They're beautiful."

"They encourage people to walk," added Edward H. Stehmeyer Jr., director of facilities, "and that's a healthy thing to do."

The CDC's Emerging Infectious Diseases Laboratory towers above a stream of recycled rainwater. Rebuilding at the Atlanta campus incorporated environmental improvements.