The world’s largest military aviation museum will get bigger after years of waiting for a massive expansion.

Air Force leaders broke ground Tuesday on a long-awaited fourth gallery at the National Museum of the U.S. Air Force in a high-level ceremony with Secretary of the Air Force Deborah Lee James, Vice Chief of Staff Gen. Larry Spencer, Air Force Materiel Command Gen. Janet Wolfenbarger and other top-ranking leaders.

The privately funded $35.4 million expansion will add 224,000-square-feet and the hopes of tourism leaders more people will visit to view one-of-a-kind experimental planes and historic presidential jets now hidden to most visitors because it requires a bus ride to get to a gallery hangar on a publicly inaccessible portion of Wright-Patterson. The new gallery would open in 2016 and also showcase giant cargo planes and spacecraft.

“It’s a huge milestone for us and it is a relief to get to this point where we’re able to get to groundbreaking,” said museum director John “Jack” Hudson.

In a brief speech to a crowd at the outdoor ceremony, James hearkened the legacy of airmen through the decades to the messages and stories found at the museum.

“When you come right down to it, living the Air Force legacy is really what this magnificent Air Force museum is all about,” she said.

The groundbreaking coincided with the Wednesday start of Corona, a yearly gathering at Wright-Patterson since 2006 of about 50 top-level Air Force civilian leaders and military commanders who talk behind closed doors about the future of the service branch. The generals and senior civilian executives will be on base through Friday, said Michelle Martz, an Air Force Materiel Command spokeswoman.

More than 1 million visitors a year visit the museum, but only about 90,000 a year have been able to see some of the most historic and important aircraft in the collection because they are in a hangar on the main base.

The planes headed for the new hangar include:

* The presidential seal emblazoned Boeing 707 that brought President John F. Kennedy’s remains to Washington, D.C., after he was assassinated Nov. 22, 1963 in Dallas;

* The XB-70 Valkyrie experimental bomber that flew at three times the speed of sound

* The hypersonic, and near orbital rocket plane the X-15.

Museum officials say the uniqueness of those aircraft attract visitors around the world to the Dayton-housed collection.

“Right now, we don’t have a way to tell these stories to the public in the way that we should,” Hudson told reporters. “This gets the public unimpeded access to all those artifacts in addition to all the other airplanes coming over here.”

A tug of war between Ohio and Texas erupted briefly when the Lyndon B. Johnson Library and Museum disclosed its plan to bring the so-called JFK plane to Austin, a move Ohio congressional lawmakers fought. The Air Force opposed the attempted move and said it would keep the plane in Dayton. The Texas museum wanted the jet because it’s where Johnson was sworn in as president immediately following Kennedy’s death.

The new building will be home to a $1.7 million space shuttle exhibit on the edge of the Cold War Gallery, three science, technology, engineering and math (STEM) learning nodes, or theaters, and bring four aircraft outdoors into the confines of the museum.

Slower-than-expected fund raising on the project in hard economic times had delayed construction by years. Last December, a never-disclosed losing contractor’s protest among five bidders delayed construction further.

The Army Corps of Engineers, which oversees the project, denied the protest. Washington, D.C.-based Turner Construction Co. was the chosen bidder.

Turner project executive Brian Moran said up to 70 workers will begin work in late July and finish in about a year. He said he expected the majority of the workers will be from the Dayton region.

The Air Force Museum Foundation has spent years raising money for the expansion. It’s raised about $39 million so far, and has a goal to bring in about $7 million more, said Francis A. Duntz, chairwoman of the nonprofit organization.

The money will pay for tow paths, lighting and STEM learning nodes, among other expenses, she said.

“We are not finished with our campaign,” she said. “We have much to do.”