Nearly 40,000 runners and thousands of race watchers will line the 10-mile route from Central High School to the Navy Yard on Sunday.
But it won't be like years past - for participants, fans or the police.
"There is no specific threat to the city of Philadelphia," said Mayor Michael Nutter Wednesday at Philadelphia Police headquarters.
But given the recent events at the Boston Marathon, Nutter laid out enhanced security measures for Sunday's run.
A greater police presence will be visible, but there are other efforts behind the scenes.
"There will be a bunch of other things that you won't see, you shouldn't see, and we're not going to tell you about," Nutter said.
We do know three moveable surveillance platforms will be moving up and down Broad Street. It's recommended runners not bring gear with them. If they do, any gear must be packed in clear bags.
Three evacuation shelters will be located along the course if there's a need to seek shelter. They are Ben Franklin High School, The School for Creative and Performing Arts, and South Philadelphia High School.
And there are rules about what's allowed in the Navy Yard, where the finish line is located.
"Bags, backpacks, coolers, and similar items are prohibited from the Navy Yard, which is at the end of the race course," said Nutter.
While authorities work on safety and security, runners along Kelly Drive are keeping their focus on the ten-miler.
Jeneen Barlow of Cheltenham, Pa. is running in her mother's memory on Sunday. Nothing, she says, will stop her from taking part.
"Runners are pretty gritty people," she told Action News. "We do what we do, most of us, for a reason. And I don't think that people are going to let it stop them. I think we're going to trust that everything's going to be fine and do what we came to do."
If you do need to report something suspicious, police officers will be located along the route and at every water station, or you can just call 911.