Staff and workmen carried duct tape and tools and made sure the giant atlas was hinged just right Friday morning in the half-hour before the National Children’s Museum at National Harbor opened its doors, returning to the Washington area after more than eight years.

Then, promptly at 10 a.m., a blue-shirted museum guy made it official: “We’re opening,” he called out and dozens of of staffers burst into applause. A line of families streamed through the doors, and all of a sudden the place got loud and busy.

The $6.7 million, 18,000-square-foot space, filled with maps, plastic foods, construction gear and interactive touch screens, felt like a play-date invitation waiting to be answered.

“I just got goose bumps,” said Michal Miller, a museum spokeswoman. It was a reaction shared by some parents who thought this day would never come.

Chris Garber of Alexandria, her husband, Andrew, and sons Ben, 3 and Luke, 2 were among the first to arrive. “We kept hearing: ‘Oh, it’s coming soon, it’s coming soon,’ but I was doubtful. I’m just glad it finally did,” Garber said.

A preview of the National Childrens’ Museum in National Harbor, MD. Pictured, Chloe Fisher, 1&1/2, right, and her sister Samantha, 3, of Centerville, try firefighters togs on for size. (Bill O'Leary/The Washington Post)

The former Capital Children’s Museum closed its H Street NE location in 2004 and functioned as a “museum without walls,” focusing on community outreach programs and partnerships in events such as the White House Easter egg roll. Though it had become the only congressionally designated children-focused museum, there were delays with funding, and a planned move to L’Enfant Plaza fell through.

Thomas M. Berger, executive vice president for the museum, said: “This is the end of the beginning. This is what it’s all about.”

The museum features a Sesame Street-themed “3 & Under gallery” for toddlers, an “Our World” gallery of maps, world culture stations and a mini-town, and a theater, which smelled like new carpet. But even if a planned 60,000-square-foot “outdoor experience,” to include an amphitheater and a Big Wheel raceway, opens in 2014, it will still lack the size of some comparable museums around the region. The Please Touch children’s museum in Philadelphia is 136,000 square feet, Baltimore’s Maryland Science Center is 170,000 square feet and Port Discovery is 80,000 square feet.

The National Children’s Museum core audience is 10 years and younger, said Berger, who noted that although science museums have activities for young children, they usually start at age 10 and up. “This is Location 1, and we fully expect that over the years we will grow,” Berger said.

By 10:30 a.m., the “3 & Under” gallery was literally crawling. “What do we have here?” a museum staffer playing reporter asked the Garber boys in the “My Town” section, which featured barrels of play imports being lifted by a play crane.

“Oh, that’s a tire,” said 3-year-old Ben, who paused for a brief tug of war with his little brother over a few wedges of Mexican cheese. Several feet away, a group of young girls were climbing all over a three-wheeled “tuk-tuk” in the “World Cultures” section and conversations got appreciably louder as one little girl laid on the horn.

Wendy DuPree, a homemaker from Springdale, said she grew up going to the Children’s Museum in the District. “I was like, when is the museum going to open? This has been on my calendar for months!”

DuPree was waiting in line to buy a membership with her mom and three kids, one of whom shared a stroller with Yodit Crouch’s 2-year-old son. “Before this opened, we were going to [Port Discovery] in Baltimore,” said Crouch, also homemaker, but the new museum is closer with better parking. “It’s such good exposure, people will be coming from everywhere,” she added, talking loudly to make herself heard over all the noise.