Every 15 minutes or so on Saturday, a crowd at Monument Square in Portland let out a cheer.

Each outburst welcomed the arrival back on solid ground of someone who had just rappelled 13 stories down the side of One City Center. Eighty people signed up to descend one of Portland’s tallest buildings by rope to raise money for Rippleffect, a Portland nonprofit youth and community development program that operates outdoor adventures.

“It was amazing and terrifying,” said Racheal Delcourt of Windham.

Delcourt had just made the 173-foot descent with Richard Veilleux of Portland. Both work at MaineHealth, one of the event sponsors.

“It just looked like too much fun to miss,” Veilleux said.

Each participant had to raise a minimum $1,000 for programming and scholarships for Rippleffect, although some raised much more. David Whiston, a Rippleffect board member, used the occasion to celebrate his 60th birthday and raise $10,000, said Anna Marie Klein Christie, executive director of Rippleffect. At the end of the day, the organization raised about $80,000.

The oldest participant Saturday was John Parker, 83, of Falmouth, who said the experience was nothing like the last time he rappelled – 40 years ago – as part of an Outward Bound excursion on Hurricane Island.

“The best adjective is, it is much safer,” Parker said.

Over the Edge, a special events company in Nova Scotia, provided the backup expertise to the rappellers, who started out on the roof, inching down the side of the brick and glass building toward the crowd below.

The roof provided a panorama, with Cow Island, home to Rippleffect’s outdoor campus, visible on one side and Greater Portland neighborhoods on the other. Participants needed no previous experience.

“It is totally safe, really safer than crossing the street,” Christie said.

It took most of the day for all of the rappellers to make the descent, either individually or by twos.

Spectators said the sight of rappellers in the middle of Portland was unusual and impressive.

“It looks so crazy,” said Janet Altobello, who traveled from Peterborough, New Hampshire, to watch her son, Devin Altobello, take his turn down the side of the building.

Olivia Harris, 6, of Hallowell waited to see her father, Aaron Harris, appear over the edge of the roof. She said it would be the highest she had ever seen him.

“I’ve seen him go up in a tree swing before,” Olivia said.

Beth Quimby can be reached at 791-6363 or at:

[email protected]