Dozens of numbers have been retired over the years by dozens of teams, but the number seven has been retired only twice. Mantle's was retired by the Yankees in 1969. On Sunday, the honor belonged to Biggio, who witnessed the unveiling of his lucky number before a packed house at Minute Maid Park that included longtime friends, colleagues, teammates and family members, all of whom gathered on the field to honor a true Astros original.
The event included speeches by teammates and coaches closest to Biggio, including longtime Astros coach Matt Galante, who worked tirelessly with Biggio during his conversion from a catcher to a second baseman.
"He would tell me, 'Don't tell me what I'm doing well,'" Galante recalled. "'I know that. Tell me what I need to do to become a good player.' He said, 'If we do this switch, I don't want to be just good at it, I want to be really good at it.'
"I said, 'Craig, if you want to do that, then you have to think about Gold Gloves.' And he won four of them."
Jeff Bagwell, who played 15 years with Biggio and whose No. 5 was retired last year, credited Biggio with redefining the mold of the prototypical second baseman.
"It's not just defense," Bagwell said. "It's offense, baserunning -- everything you see now from second basemen, it started with Craig. He was truly one of the greatest players who ever played this game.
"I can't tell you how privileged I am to have had the chance to play with him for the last 15 years. You're an amazing player, an amazing father, an amazing husband. Anyone with a child sitting next to them -- you want your child to grow up and be Craig Biggio."
A special highlight for the honoree arrived when 15-year-old Conor Biggio, the eldest of the three children, gave a speech that was both touching and funny, especially when he poked fun at his dad for some of his well-known strategies at the plate.
"He would do anything to help his team," Conor said. "Even if it was by accident -- like when he 'accidentally' moved his arm out, and 'accidentally' got hit by the pitch.'"
Conor said his dad was resourceful, using only two helmets at Minute Maid Park, both of which were, according to the eldest Biggio son, "just nasty."
"He would chew a piece of gum, and when it was time for him to bat, he would stick the piece of gum in his helmet and save it for later."
As the crowd laughed, Conor added, "That nasty helmet you saw on the outside had gum stains all on the inside."
Biggio's kids presented him with a collage of photos of their childhoods, ranging from their earlier years to modern times.
The Astros also presented Biggio with gifts -- three jerseys, each from a different era of his 20-year career, and a John Deere infield groomer for the baseball team at St. Thomas High School, where Biggio serves as the head coach.
"[Bagwell] volunteered to come over and drive it and help get the diamond in good shape," club owner Drayton McLane joked.
The ceremony continued with a video presentation highlighting the best of Biggio's 20-year career. It began with old footage of an interview with Biggio's college coach from Seton Hall talking about "this kid, Biggio, who could really be something special."
The list of on-field guests included Biggio's immediate family, his mother, Johnna, and his brother, Terry, who is home from a year-long tour in Iraq, where he voluntarily helped to rebuild the air traffic control system.
The late Ken Caminiti's family, long considered family to the Biggios, also attended -- Caminiti's wife, Nancy, and their three daughters, Kendall, Lindsey and Nicole.
Biggio also thanked former Houston second baseman and fan favorite Bill Doran, who more than a decade and a half ago flew to Houston to help Biggio properly make the conversion from catcher to second base.
Most of the living retired numbers were there, too -- Bagwell, Jose Cruz, Mike Scott, Larry Dierker and Jimmy Wynn, as were three behind-the-scenes contributors who played huge roles in Biggio's success. He described traveling secretary Barry Waters and clubhouse manager Dennis Liborio as the "backbone of the franchise," while thanking his agent Barry Axelrod for his role in making sure he finished his career in a Houston uniform.
The event ended with Biggio throwing the first pitch to his good friend Brad Ausmus, who jokingly crouched five feet in front of home plate before moving back to the normal position.
Biggio gave that ball to his brother, Terry, whose time in Iraq last year forced him to miss Biggio's 3,000th hit, his retirement announcement and his final game.
"My kids have plenty," he said. "[Terry] deserves it. He's been a great brother to me, he works hard, he's a good man."
To the fans, Biggio's message was simple but poignant.
"Thank you for sticking with me through the years," he said. "Thank you for being Astros fans. Thank you for being fans of the game. I think the coolest thing about Astros fans is they love the logo, but they truly love the person that wears it more."