PITTSBURGH (AP/KDKA) – About 40,000 runners will participate in the Pittsburgh Marathon or half marathon on Sunday, and those and other shorter events on Saturday will be closing several key roads downtown and elsewhere in the city.

The first road closure begins Friday on Boulevard of the Allies, which closes between Wood and Stanwix streets at noon. That’s so organizers can prepare a finish-line area for several activities related to the race.

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Most of the other closures begin Saturday morning in preparation for a 5K race and other events, including a Kids Marathon one-mile run, that day. Click here for a full list of road closures.

“Two-year-olds will be running in the Toddlers Trot. And there’s an 86-year-old who signed up for the half marathon.  It’s for all generations,” Allegheny County Executive Rich Fitzgerald said.

The full and half-marathons will be run Sunday.

About 350,000 people are expected to watch the race at some point along the 26.2-mile course.

What draws people to Pittsburgh for this run? Several participants weighed in.

“Here you’ve got the hills, you got alleys, you got flat surfaces. Its wonderful. Plus, its a beautiful place to tour,” Teak Denard said.

“I think its the challenge of preparing. You prepare for almost half a year sometimes. And just the event itself. Just having a group of people, all coming together to achieve something,” Sean Williamson said.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)