The Dublin Fringe Festival is urging people to engage with the city, for starters by setting it on fire, writes Peter Crawley

With enough time, all cities become invisible. It isn't that they disappear exactly, but through over-familiarity, the unthinking journey to work, or the safe cocoon of an iPod, their details begin to blur into the background. In Manhattan, for instance, it is understood that only tourists gaze up at the skyscrapers.

For an artist, making the city seem vivid again in the eyes of its inhabitants requires extreme measures or surprise attacks. From spontaneous "happenings" of performance art in the 1950s to the hipster street performances of "flash mobs" in the noughties, city performances involved sudden invasions. The conceptual artist Christo has used enormous gestures to reawaken several cities, wrapping the Pont Neuf in 40,000 metres of fabric and similarly enshrouding the Reichstag so that familiar landmarks could be seen in new ways.

This year, the Dublin Fringe Festival - or the Magnet Entertainment Dublin Fringe Festival to give it its full title - has ambitious plans to reconnect Dubliners with their capital. First, it is going to set the city on fire.

When the festival begins, on September 9th, la Compagnie Carabosse will set George's Dock alight with a fire installation. Since 1997, the French group have perfected the technique of fire pots, in which flickering flames and plumes of smoke are used to illuminate public space. Plans are also afoot to have four-metre fireballs illuminating the city, with fire pots positioned across the Ha'Penny Bridge and a giant flaming chandelier dangling over the Liffey. According to Wolfgang Hoffmann, now in his second year as the festival's director, this has sparked some nervousness among the event's co-commissioners, Dublin Docklands Development Authority, and its sponsors Dublin City Council.

"In general there was a great sense of doubt and caution about the fire thing," Hoffmann shrugs, bemused, perhaps, by the Council's concept of Dubliners inclined toward self-immolation. "It needs to be a balance between making it safe and, at the same time, making it an experience: you can't put the flames behind fencing when the whole idea is that you must have the shine of fire in your eyes and its warmth in your heart to feel moved." It is, he agrees, a Christo-inspired manoeuvre of "bringing light and colour into the city and therefore making everybody's life better in a small way".

Public art is clearly the mainstay of this year's fringe festival, which, more than any other year, treats performance and exhibition like a municipal service. This year for instance, you may encounter the Canadian company Corpus's human sheep, grazing happily on the grounds of St Stephen's Green. You can participate in one of two separate guided tours through a city made unfamiliar, or stride along the Liffey boardwalk, your path from the Ha'Penny Bridge to George's Dock illuminated by 150 custom-designed lanterns. The events may be wildly different, but their intentions are the same: to actively engage with the city.

"We wanted to make the work accessible," says Hoffmann, "and not only to art consumers per se and middle-class theatre goers. The Lantern Project is an idea I felt was needed - to put something in people's way, almost. Nowadays people don't have time to relax and to engage a different part of their brain. The purpose, or the task, of art is to do that."

Hoffmann, who moved to Dublin from Potsdam in 2004, noticed that while the river is "an engagement point" in any other city, in Dublin, "it's more a dividing line between the south and the north. I think this lantern project will celebrate the river and celebrate diversity."

Similarly diverse, the sponsorship for each lantern comes from a separate local business, while the designs for each lantern range from maps of the transport system to mechanical apartments. All of which, Hoffmann cannily acknowledges, will form a "yellow brick road" leading to the Spiegeltent, the festival's popular performance venue and club.

"I think there's a great deal of visibility and excitement this year," he says, "which hopefully will affect people who go about their daily business."

This is also the agenda of Out of Site, a performance art project curated by Michelle Browne, in which 16 performances will "just happen" in various outdoor locations around the city. Browne is a firm believer in "the accidental audience" and this playful and accessible example of "guerrilla art" exists not to be sought out, but discovered. "I'm really interested in this idea of art blending in more with real life," she says. "People don't feel they have to have read up on it. They look at it to see if it relates to how they use the space, or how they feel about the space they inhabit. But there isn't an audience waiting at 1 o'clock for it to happen. It's about being there."

If site-specific performance has been a recent fad of the fringe festival, leading us from car-parks to churches, warehouses to disused public toilets, the new vogue is for promenade performances, or more specifically, guided tours. This year two productions - It's an Audio De-Tour and On This One Night - will take audiences through Dublin. "I'm kind of sick of sitting in the dark and watching other people do things," says Maebh Cheasty, choreographer with the Audio DeTOURists. Her response has been to drag the stage out into the light and to make the audience her performers.

Taking instruction via Mp3 players, Cheasty's audience are given "really specific choreographed instructions of how to move around the city." It's not a traditional tour - most of the stories are fictitious - but the audio tour is designed to make people see the city anew. Cheasty admits that safety is a concern, and so they perform during the day, avoiding insalubrious routes. "We don't want to make people feel ill-at-ease. But that idea seeps into the tour as well: who owns public space? Is this space yours? Can you feel safe here?"

The answer in On This One Night is probably no. Restricted to an over-18s audience, Brokentalkers' production dubiously promises us, "You will be taken into the belly of the beast . . . you will break the law and get away with it".

Co-artistic director Gary Keegan admits that patrons are not required to commit homicide, but may be invited to jaywalk. "It's a city you don't know as well as you might think," says Keegan, who outlines the show's theme as "Dublin by Night". "By changing the context of a simple walk, by changing the route, it certainly shifts your perception of the place."

The unspoken tension with public art and outdoor performance is that without the shelter of the gallery or the theatre space, both are vulnerable to intrusion, disruption or even destruction. When CowParade, an installation of individually decorated cow sculptures, came to Dublin in 2003, many sculptures were vandalised. "I think it would be wrong to let us be put off by that," Hoffmann said of The Lantern Project when I mentioned CowParade. "Of course you can't guarantee that we won't have the same kind of issue, but I would totally want to refrain from over-reaction, like needing security guards. One needs to continue making work and putting work out there."

Michelle Browne was wary of interference, too, but seemed more concerned at the prospect of having her Dublin City Council-approved performances halted by gardaí as "obstructions to traffic" than of receiving heckles from the street. "I think what's really interesting about it is that this is art for public space," Browne said. "And then you discover that it's really run and managed - and sometimes feels like it's owned - by a lot of other interest groups, and not the public."

Gary Keegan was more sanguine about interruption. "In previous shows, there were a couple of interventions that left the audience wondering, Was that part of the performance?" Brokentalkers tour guides were able to handle the intrusions skilfully, but Keegan liked the ambiguity they introduced. "Everything is potentially part of the performance and therefore the audience really switch on: they watch everything. And that's where the shift in perception happens."

This, you feel, is the effect that the Fringe lusts after this year. Its public displays of fire pots, lanterns, guided tours and guerrilla art are a combined effort to jolt the city back into a sharper view, and perhaps even to transform it in our eyes, if we just take the time to look.

• The Magnet Entertainment Dublin Fringe Festival runs Sept 9-24. See www.fringefest.com