Architect Peter Chermayeff was 38 when he got a phone call about the possibility of designing an aquarium for Baltimore's waterfront.

Housing commissioner Robert C. Embry Jr. had visited Boston's popular New England Aquarium, which opened in 1969, and envisioned building a similar attraction for Baltimore's Inner Harbor. Aware that Chermayeff led the design effort for New England, Embry wanted to hire him for Baltimore as well. It was an enormous responsibility for such a relatively young architect, but Embry didn't consider it a gamble.

Chermayeff was a "very strong designer" with a good reputation for working in an urban context, Embry recalled recently. Plus, he already had designed one aquarium for a waterfront setting similar to Baltimore's. "It seems to me that it would have been a gamble to go with anyone else."

Embry's overture to Chermayeff led to the creation of the National Aquarium in Baltimore, the seven-story aquatic museum that recently celebrated its 20th anniversary. Besides forming the sculptural centerpiece of Baltimore's Inner Harbor, it's one of the most successful aquariums in the United States, drawing 30 million visitors since its opening and setting off a wave of aquarium construction around the world.

Now Chermayeff is back for an encore. With longtime partners Bobby Poole and Peter Sollogub, he's designing a $48 million addition to the Pier 3 building, a glass-enclosed structure that will extend the aquarium's global reach and give visitors new reasons to return. But this time he is no neophyte at aquarium design.

Since Baltimore's aquarium made its debut, the Massachusetts-based architect has become an international leader in aquarium design, with six major projects open and many others on the drawing board. Besides Boston and Baltimore, he has completed aquariums in Chattanooga, Tenn.; Osaka, Japan; Lisbon, Portugal; and, in collaboration with Italian architect Renzo Piano, Genoa, Italy. He is working on aquariums for Virginia Beach, Va.; Islip, N.Y.; New Bedford, Mass.; Hartford, Conn.; Coralville, Iowa; Homestead, Fla.; and Shanghai, China.

In 1998, Chermayeff left the firm he helped start in 1962, Cambridge Seven Associates, and established a new office that specializes in aquarium design -- one of the only companies in the world that does so. Its name is Chermayeff, Sollogub and Poole Inc., or CSP, and all three name partners played key roles in the design of the National Aquarium.

For the past 11 years, Chermayeff also has been president of a second firm, International Design for the Environment Associates Inc., or IDEA. It's a company devoted to the design, development, construction and operation of aquariums and other "nature related attractions."

After creating buildings for others over the past four decades, Chermayeff is now working to fulfill perhaps his most ambitious goal yet. He wants to own an aquarium -- one that he designed, filled with creatures and operates. After exploring numerous locations over the past decade, he finally may get a chance to do that in Dusseldorf, Germany.

Chermayeff's plans cross the traditional lines that separate architect, builder and client, and may lead to conflicts with some of the institutions with which he already works. That's an unavoidable byproduct of the stature he has attained since accepting the challenge to design Baltimore's aquarium -- and his desire to accomplish even more.

"Most architects would consider themselves fortunate to have completed one major public building in their lives," he observed during a recent visit to Baltimore. "We've been fortunate to have eight or more, with others to come."

In town to attend the aquarium's anniversary celebration, and looking not much different than he did the day it opened, Chermayeff said he'll always be grateful for the early support he received from Embry and then-Mayor William Donald Schaefer.

Even more than the New England Aquarium, he said, Baltimore's project propelled him on a career in aquarium design because he learned so much from his work here and so many key decision-makers wanted to replicate it in their cities.

Chermayeff says he's especially pleased to have been invited to work on projects such as the Lisbon Aquarium, a key attraction of the 1998 World's Fair in Portugal.

"When the leaders of another country and another culture want me and my colleagues from America to design a building that will be the centerpiece of their exposition," he said, "it's a great honor."

From tadpoles to aquariums

Now 65, the father of two, Chermayeff is the quintessential Boston Brahmin, in hand-tailored suits and round spectacles. Erect, proper, unfailingly polite, he has a trace of a British accent when he speaks, which is always eloquently and with great conviction. But there was a time when he wasn't sure he would practice architecture at all, much less specialize in aquariums.

The chief designer of Baltimore's aquarium was born in London in 1936, the son of Russian-born architect and educator Serge Chermayeff. He emigrated to America with his family during World War II, attended Phillips Academy in Andover, Mass., and studied architecture at Harvard University, where his father taught the same subject.

The young Chermayeff was exposed to nature and the world of water in a variety of ways. As a boy, he spent summers collecting tadpoles and newts on Cape Cod, where his family had a vacation home. While at Phillips, he spent many weekends with his "second family," architect Walter Gropius and his wife, both serious birdwatchers.

Though he considered himself an "amateur naturalist," Chermayeff said, he took no college courses in marine biology or natural history. After graduation from architecture school, he seriously considered becoming a filmmaker.

Just when Chermayeff was at his most ambivalent about practicing architecture, a friend, Paul Dietrich, suggested that the two join with several others to form a design collaborative. The idea was to start a new kind of interdisciplinary firm that would combine architecture, urban design, graphic design, exhibit design, industrial design, landscape design and even filmmaking. Other prospective members were Alden Christie, Louis Bakanowsky, Terry Rankine, Tom Geismar and Chermayeff's older brother, Ivan, a well-known graphic artist. Chermayeff was intrigued, but decided they needed a project first.

In his early quest for commissions, Chermayeff met with the director of Boston's Franklin Park Zoo about improving its property. The zoo had no money to hire an architect, but the director was impressed by Chermayeff and his colleagues and told them about another group that planned to build a public aquarium on Boston's waterfront and needed an architect.

Public aquariums have been around since the early1800s in the United States and Europe. Turn-of-the-century French writer Paul Claudel once described them as "the link between art and nature." One of the first was created in New York by P.T. Barnum, better known for his traveling circuses. In many cases, the early aquariums were housed in neo-classical buildings that resembled museums, with tiny fish tanks on the walls in lieu of framed paintings.

The Boston group wanted to break the mold. Its aquarium, planned for a pier near Faneuil Hall in Boston, promised to be the ideal commission for the firm Chermayeff and Dietrich were contemplating.

With the zoo director's help, Chermayeff and his colleagues landed an interview. The night before the meeting, they printed stationery for their new company. By far the youngest architects considered, they were up against some design heavyweights. To their amazement, they got the job. Cambridge Seven Associates was born.

When it opened seven years later, the New England Aquarium was a showcase for Cambridge Seven's interdisciplinary design approach. The exterior was a relatively subdued concrete box that fit in with other warehouses on Boston's waterfront. Inside was a burst of color and activity -- an aquatic show world. It was just what the sponsors wanted -- a building that took aquarium design in a new direction, artfully combining entertainment and education.

That's what impressed Embry, who was on the lookout for new ideas to try in Baltimore. At first, Embry said, Schaefer wasn't particularly interested in seeing Boston's aquarium. But after Schaefer toured it and realized its potential, he was hooked -- and wanted one for Baltimore. Happy to build on what they learned in New England, Chermayeff and his partners agreed to design it.

Although both projects were set for the end of a pier, Baltimore's aquarium had the potential to be much more dramatic architecturally than New England's, which was designed for "the reticent simplicity of Boston's old waterfront," as Chermayeff put it. "We decided that in Baltimore, we should be more boldly expressive of what we were doing."

The strategy worked. Even before it opened, the building won a national award for its design, which has been likened to the Sydney Opera House in the way it juts into the harbor. The interior was notable, too, for taking visitors on a simulated journey from the bottom of the Atlantic Ocean to the top of an Amazon Rain Forest. Again featuring Cambridge Seven's trademark mixture of architecture and exhibit design, the building became known for its one-way circulation sequence, back-lit graphics and dark, Piranesian spaces.

Chermayeff was particularly proud that Baltimore's aquarium was the first in the country to give a terrestrial exhibit -- the rooftop rain forest -- equal weight with aquatic exhibits. "It's not just a token exhibit stuck in the corner," he said. "It makes the point that all life is dependent on the water, and, in fact, unified by water."

Striking architecture and beautiful, immersive environments have always been keys to the aquarium's appeal, said former aquarium executive director Nicholas Brown.

"I think this aquarium succeeds because of the genius of Peter Chermayeff," Brown said shortly before his retirement in 1995. "He built it and builds his aquariums one way. There are other ways to build aquariums, and there are many other successful aquariums. But there are no successful aquariums that do not pay homage to the god of beauty."

Forerunner to a boom

In many ways, Baltimore's aquarium was to its industry what Oriole Park was to sports stadiums and Harborplace was to festival markets -- the project whose success spawned copies all over the country. It wasn't the first to be completed, but it was the best for its time -- and the one that got the most attention as a result.

It also addressed a need. City leaders liked the idea of building aquariums because they tapped into the spirit of the age in several ways. They spoke to the effort to rejuvenate cities, the push to protect the environment, the quest to increase tourism and provide a place where young parents can spend time with their kids. Zoos take up vast stretches of land, but aquariums are relatively compact structures that can be combined with other attractions, such as hotels and IMAX theaters, to become engines of economic development for their communities.

By the mid-1980s, cities were racing to open these "underwater zoos." Before Baltimore's opened, Chermayeff said, he didn't think Cambridge Seven would be commissioned to do many more. After Baltimore, he said, prospective projects "started to fall out of the sky."

With each project, Chermayeff and his colleagues got the chance to explore new directions and tell different stories -- freshwater environments instead of saltwater (Chattanooga), taking a regional focus (Seward, Alaska), interweaving human history with natural history (Genoa), working inside a recycled building (New Bedford), exploring the wonders of ice and glaciers (Islip).

In every case, Chermayeff found a way to take plants and wildlife that may seem ordinary in nature and exhibit them in such a way that they seem out of the ordinary. His buildings are not so much museums as theaters -- with living creatures as the featured players, performing not according to scripts but natural behavior. "The key," he says, is "to find the intrinsic interest, the excitement, in what seems ordinary but isn't."

The more aquarium design work Chermayeff did, the more of an expert he became. Others may have been considered for certain aquarium commissions, but they didn't have the design experience he did, or the penchant for taking an interdisciplinary approach.

"What sets us apart is our interest not in pure architecture but in the combination of architecture and exhibit design and graphic design and landscape design," Chermayeff said. "It adds an extra dimension to what we're doing."

For every aquarium that was built, many others failed to materialize. Cambridge Seven developed proposals for Denver, Moscow, Dublin, London, Glasgow, Hamburg, Toronto and Ottawa, among other cities. One project that Chermayeff regrets not completing was a plan to turn New York's Radio City Music Hall into an attraction called Ocean World, with legendary oceanographer Jacques Cousteau as a partner.

Whether the projects moved ahead or not, Chermayeff was gratified to have so much work. It combined the chance to create striking architecture and help renew cities with the chance to explore and celebrate nature -- an unusual mix.

"In many ways, what we've enjoyed doing is finding diverse ways in which urban settings, where people are often deprived of any contact with the natural world, can become better connected with nature" through realistic exhibits, he said. "The artistry of creating exhibits has come a very long way since the 1960s."

One underlying goal of his is to connect people with other living creatures by setting up encounters that stimulate an emotional response. The more varied and realistic the experiences are for aquarium visitors, he says, the more likely they are to be moved by what they see.

"The encounter is what it's all about," he says. "The aquarium is intended as an immersion experience, where visitors will be surrounded by the animals and feel their presence all around. We've tried to get the interior architecture to be so secondary it seems to disappear."

Changing message

Twenty years after the National Aquarium opened, the nature of aquarium design has changed significantly. There is less emphasis on creating settings in which dolphins jump through hoops, and more emphasis on conveying a message about the need to conserve the world's natural resources.

In many cases, the architects are reducing the amount of written information for visitors to digest, so they can concentrate on the living creatures. They're always trying to create more naturalistic habitats -- even if that means downplaying or eliminating architectural infrastructure. Many of their newest buildings are enclosed by glass, rather than concrete, as owners attempt to make exhibits more visible and accessible.

"It's not just about architecture," Chermayeff said. "It's about places. We're choosing less complex subject matter but getting more into it so we can go deeper. We don't just want to show dolphins. We want to find ways to show how intelligent they are and make the point that they have complex social lives. If we can pull it off, it's a richer experience for people."

Over the past decade, IDEA has assembled aquarists from around the world, including former staffers from aquariums that Cambridge Seven designed, to operate aquariums under its purview. In a sense, the aquariums that Chermayeff designed are becoming the training grounds for experts who will run the aquariums he's designing for the future.

For Chermayeff, the ultimate extension of that process would be owning and operating an aquarium. Architects have become developers in the past, for projects ranging from housing to hotels, but this would be a first. And it raises more than a few questions about the traditional separation between architect, client and builder. Who could he test his ideas against when he is both client and designer? Where are the traditional checks and balances?

Chermayeff said he understands the potential pitfalls. But he believes there can be advantages when the builder of a complicated structure or exhibit is the same as the designer. Ideally, he said, it could improve the way aquariums are designed and built -- and, ultimately, the experience for visitors.

"We've always thought we could hold to a higher standard if we had more of a say," he said. "There could be tremendous benefits to the whole process."

Untiring worker

At a time when many architects consider retirement, Chermayeff is busier than ever and energized by his latest work. He said he's especially grateful that directors of the Baltimore aquarium came back to him and Poole and Sollogub to design the building that will be attached to the one on Pier 3.

In Boston, the New England Aquarium hired another firm to design an addition, and it dramatically altered (some would say marred) the look of the original. The National Aquarium hired another architect to design its Marine Mammal Pavilion. But on Pier 3, at least, decisions that will affect the look and use of the original building are being made by those who designed it.

That was never in doubt, said Mark Seely, senior director of capital planning and facilities. "We thought it was very important to have the original architects involved."

Although Chermayeff is too diplomatic to say which aquarium is his favorite, it's clear that he will always have a special place in his heart for Baltimore's.

"I feel this building and this institution have been the pleasure of a lifetime," he said. "I put my heart and soul into it, and it has remained dear to me ever since."

While he now operates on many fronts at once, he says he'll never tire of the work because it's always changing.

"I like to think that, with each project, we're achieving something new," he said. "That's the search, anyway. That's what keeps us going."