Waiting for them was a white-gloved honor guard of Transportation Security Administration agents standing at attention; a cheering, flag-waving crowd; and a red, white, and blue display with blown-up photos of the uniformed Marinis during the war.
"You might have thought I did something important," said Marini, 87, who served in Europe toward the end of the war. "I don't know what all the fuss is about.
"I'm almost at the point of embarrassment," he said. "What happens when a real celebrity comes here?"
Hank Marini, 92, of Ridley Park, was equally surprised by the meticulous preparations when he arrived Monday at the airport to meet his brother.
"I didn't expect this," Marini said. "This whole thing is amazing, amazing."
Much more awaited the brothers as they made their way through cheering crowds at the airport to a specially equipped van and motorcycle escort that rivaled any accompanying a president.
Hank and Louis, who grew up in South Philadelphia, are the last of six brothers who served - five during World War II and one during the Korean War. A sister is also living.
"All of us came home unharmed," Hank Marini said. "Everything in life is timing.
"I had a lot of luck in my life - a good wife, good kids, and good grandkids," he said.
Hank Marini was drafted into the Army in 1943 and sent to Greenland, where he was a mechanic, observer, and height finder in an antiaircraft battalion - he helped determine the height of enemy planes so they could be effectively targeted. He was discharged in January 1946.
Louis Marini was drafted into the Army in 1944 and deployed with the Third Army to France and Germany. He was discharged in August 1946.
The common war experience forged another kind of brotherhood between Hank and Louis - and prompted them to want to visit the World War II Memorial. Family commitments prevented them from going earlier.
Then Hank Marini learned about a June 21 trip planned by Honor Flight Philadelphia, a nonprofit that has helped transport more than 82,000 veterans to the memorial since 2011 - at no cost.
He knew his brother wanted to see the site, too, and told Honor Flight, which arranged - through tickets donated by Southwest Airlines - to fly Louis Marini free to Philadelphia.
"I just believe [World War II veterans] need our thanks," said Joe Sciara, a Honor Flight Philadelphia volunteer and US Airways flight attendant who helped organize the airport event. "They never got a proper welcome.
"Every time we do this," he said, "there's a burst of adrenaline."
Offering the veterans a trip to the memorial is another way of thanking them for their service, said Sciara, of Center City. More than 1,000 of them - most in their 90s - are dying every day.
Hank Marini; his wife of 60 years, Lois; and daughter Diana DiMattia, of Glenolden, were picked up in Ridley Park by an Honor Flight van and brought to the airport, where they soon became aware of the effort that had gone into the event.
Hank Marini marveled at the large photos and the TSA honor guard that accompanied him to the terminal, where he saw flags and patriotic decorations.
Joining Honor Flight were Southwest Airlines employees; representatives of A Hero's Welcome, a nonprofit organization hat arranges welcoming celebrations for veterans; and Warriors' Watch, a patriotic motorcycle organization that honors veterans.
"I'm glad to see this," said Lois Marini. "They deserve it."
After the fighting ended in 1945, "they got back and said, 'We won the war, and now we can go on with our lives,' " said DiMattia, a nurse.
Nearby, Hank Marini posed for photos with family and friends. "I feel like a celebrity," he said.
"You are," said professional photographer Kyle Morris, who was shooting pictures of the event.
Marini stood in the middle of the TSA honor guard at attention while a crowd of people holding flags waited.
No one cared whether the Marini brothers had distinguished themselves in combat and won a chestful of medals. They represented all World War II veterans, and the public's admiration and respect for them.
"They're treating me like a general," said Hank Marini, a retired production planner who worked for Boeing. "My brother is going to have a heart attack. . . . This is hard to believe."
All the passengers filed off the airliner ahead of Louis Marini. "I've never seen anything like this," said passenger Hugh Smith, 52, of Kansas City, Mo., as he readied his cellphone camera. "When I saw all this, I said, 'Whoa!' "
Louis Marini was brought out in a wheelchair to cheers, applause, and a hug from his brother. The two had not seen one another for nearly 10 years.
"On behalf of the Department of Homeland Security, the Transportation Security Agency, and Philadelphia International Airport, we welcome you to Philadelphia," said a TSA agent.
"I can't believe all this commotion," said Louis Marini, a retired electrical contractor. Medal of Honor hero "Audie Murphy didn't get this much."
As the Marini brothers moved through the airport, people they didn't know said, "Thank you for your service," and "God bless you." Many cheered and applauded.
The Warriors' Watch greeted them in the baggage claim area with a forest of American flags, then accompanied them with a long line of rumbling motorcycles to Hank Marini's home.
"The hero thing? I'm sorry, I can't buy that," Louis Marini said. "The real heroes are not here. They're buried."
"This is very thoughtful," said Hank Marini. "We never expected this."