A 17-year-old Moldovan exchange student came to Jamaica Plain Saturday, struggled with (then ultimately conquered) climbing two separate rock walls, and chowed down on her first-ever roasted Twinkie in celebration.

In other words: just another day at the office for Nira Rock.

REI held its third annual Twinkie Roast at Nira Rock Saturday, an event that included a free rock climbing workshop. Dragalina Birsan, a junior at Marlborough High School as part of the Future Leaders Exchange Program, started on the 25-foot "beginner" climb with nervous laughter and playful jokes from her host parents that involved her brains spilling all over the puddingstone rock face. For a few minutes she struggled mightily, dangling just inches off the ground, facing away from the wall at one point. And then something happened.

She started dominating.

Birsan scurried up the wall, back down, and eventually moved on to the more challenging, more technical 40-foot climb on the other side.

No sweat.

"It was harder than I thought," said the 17-year-old, who climbs unfinished buildings and monuments for fun in her Eastern European homeland. "I thought it would be easier. I liked it up there; it felt like I wanted to go further. It was nice."

Birsan's interaction was undeniably unique, and yet it's just another thread woven into the age-old quilt that is Nira Rock.

According to the Friends of Nira Rock Web site, 300 million years ago (when Jamaica Plain was on the Earth's equator and connected to what is now Western Africa) conditions were ripe for a very particular brand of stone. When early Americans settled Jamaica Plain they noted it looked like a fruit-infused Christmas pudding popular in England, and as a result dubbed it puddingstone.

The area it was found in was named in its honor. "Rocksberry" later became what is now known as Roxbury. In 1933, as the country climbed out of The Great Depression, the National Industrial Recovery Act -- NIRA -- set out to put Americans back to work, and the puddingstone was quarried. It took the name of the legislation that put it back to work.

All that remains today are the "hidden gems" off Nira Avenue in JP.

Through much of its modern history, Nira Rock was a neglected symbol of an underdeveloped, unappreciated, unwelcoming place. In the 1970s and 1980s Nira Rock was, as Friends of Nira Rock Co-Director Will Crosby puts it, "a place where people go to do what they can't do anywhere else." At best, it was a place kids went to drink and have sex. At worst, it was home to horrifying acts of inhumanity: muggings, drug abuse and rapes.

"What I've realized is public space like that either makes a community feel lousy about itself or makes a community feel great about itself," Crosby said. "We've sort of spiraled up which is really cool and it's been very exciting to be a part of."

The tide turned late in the 1980s, when the Boston Natural Areas Network looked into redeveloping the rock and eventually had it officially classified as an "urban wild" – essentially land owned by the city that it didn't have the money to develop. Today it's still an urban wild, but through the work of groups like the BNAN and Friends of Nira Rock, along with grants from the city and from corporate sponsors like REI, it's a burgeoning inner-city nature haven.

Aside from the two rock walls, there's an orchard with cherries, apples, plums, pears and blackberries. Friends of Nira Rock is holding more events like Saturday's, including movie showings in the summer, yoga in the mornings and an upcoming winter solstice event. Since Nira Rock is a public space, climbers are welcome to scale the puddingstone whenever they like. REI donated anchors that stay in place year round. People are often found walking their dogs and babies, meditating or just simply enjoying the space for what it is: a little piece of nature tucked away in the heart of an old, historically rich city.

"Sometimes I think, 'Well it's just this grubby little place, why do I care so much about it?'" Crosby said. "And then I think … 'Well, what if it wasn't here and this was just 18 more houses?' I think the difference is hard to quantify, but if it was 18 more houses the neighborhood would just feel more buried. More anonymous, more buried, less connection to something besides just people and density and houses and dirt and graffiti and trash."

Last summer a rabbit made the Nira Rock property its home. A coyote also briefly did the same. Monarch butterflies can be spotted landing on the milkweed plants. And then, of course, there's the orchard with its bounty of fresh fruit.

All of this just serves as more compelling evidence about where Nira Rock is, how far it has come, and what a sunny future lies ahead.

"Once you get the community invested in the property it starts to take care of itself," said Dane Tullock, an REI Outreach Specialist who works with the Friends of Nira Rock. "It's one of the most amazing things. It's kind of the opposite of the broken window theory. If there are buildings with broken windows, crime and other things tend to move in. But if you fix that window or you fix that property the exact opposite happens. The neighborhood gets invested in that property. People start to come and utilize the property and it becomes a really great community resource. There's a lot of cool stuff happening right here in the heart of Jamaica Plain."