John F. Kennedy was president. Gasoline cost about 30 cents a gallon. The median home price across the U.S. was just over $19,000. And arguably the coolest building in Tacoma was the brand new aquarium at Point Defiance Zoo and Aquarium.

The year was 1963. Now, after 55 years as an attraction for millions of visitors, the zoo’s North Pacific Aquarium is a memory.

The round centerpiece of the zoo’s 29-acre campus closed to the public as a saltwater aquarium on March 30.

The closure was a bittersweet moment for aquarium fans and zoo employees who were sad to see the end of the building’s public life as home to a variety of fish and other sea creatures, but who also are eager for the opening this summer of its successor – the 35,000-square-foot, state-of-the-art Pacific Seas Aquarium.

Construction of the new Pacific Seas Aquarium was made possible by Tacoma voters, who approved money to build it as part of a Metro Parks Tacoma bond issue in 2014.

The zoo’s South Pacific Aquarium, home to 16 large sharks, dozens of tropical fish, Stingray Cove and the popular Eye-to-Eye Shark Dive program, isn’t closing. When the Pacific Seas Aquarium opens, zoo visitors still will have two aquariums to explore.

The old aquarium “played a crucial role in the growth of the zoo and helped generations of our guests learn more about the fish and other sea animals that live in Puget Sound and the waters of the northern Pacific Ocean,” said John Houck, deputy director of the zoo and aquarium. Zoo officials are confident the new aquarium will carry on that legacy – with an added benefit. Not only will it showcase animals from the North Pacific Aquarium, its 275,000-gallon Baja Bay habitat will be home to an array of tropical fish. Plus, visitors will see three species never before seen at Point Defiance — green sea turtles, scalloped hammerhead sharks, and spotted eagle rays.

Over the years, thousands of people attended weddings and receptions, company parties and other events on the top floor of the North Pacific Aquarium, overlooking its once-novel cylindrical, two-story saltwater exhibit.

Closing it to the public is necessary so the aquarium team can use the entire building to care for the animals that are already there, plus new sea creatures coming in, before they move to their new homes in the Pacific Seas Aquarium, officials explained. Once that work is over, the saltwater will be removed in preparation for potential use of the building for another purpose — a proposed South America exhibit that would require significant additional funding. Meanwhile, zoo officials are considering possible shorter-term uses for the structure.