Now the Dodgers' hitting coach, McGwire stepped onto the field at the Coliseum on Tuesday for the first time since 2001 and said it's great to be back.
"We had the first three out of four years to go to the World Series, unfortunately only winning one here," McGwire said. "We had great teams. The great players that I've played with, the Hall of Fame players I've played with, Hall of Fame manager -- it's some great memories."
Though McGwire looks back fondly on his time in Oakland, he said he believes it's not the defining stop of his career.
"I was here for almost 12 years, and I was with the Cardinals for four-plus, but people remember me more with the Cardinals than they do with Oakland," he said.
McGwire said he's enjoyed working as the Dodgers hitting coach and relishes the opportunity to mold the games of up-and-comers like Yasiel Puig and Joc Pederson, among others.
He said he didn't really learn how to hit until 1992. McGwire finished the 1991 season batting .201 with 22 home runs, and the next year he hit .268 with 42 blasts.
Though he loves his current gig overall, he said it can be very time consuming and frustrating. Sometimes, he said, he goes home after a tough day and doesn't sleep well.
"I treat it like when I was a player," McGwire said. "I'm trying to pass on knowledge of what these pitchers are trying to do, and sometimes when you don't execute, those are restless nights -- same thing as when I was a player."
McGwire said he would never rule out taking a job as a manager if were offered one. It would depend on the location and other factors, but he'd consider it.
For now, though, he's simply happy to be back at the place where his Major League career got started.
"A lot of memories," he said. "The foul grounds, the wind, the scoreboard, I see spots I used to wear out over the fence, so great memories."