Attention night-crawlers, avant-gardists, bikers, party crashers and insomniacs: This one's for you.

The Twin Cities' first-ever Northern Spark festival is an all-night party at which about 200 artists will roll out 100 projects at 35 or more venues. Sprawling through Minneapolis and St. Paul, the event will hug the Mississippi River and spill over into both downtowns and neighborhoods.

High-profile locales including Walker Art Center, the Minneapolis Institute of Arts and Landmark Center are involved, but Northern Spark is not institution-centric. It's more of an up-from-the-underground effort by a bunch of quasi-subversive techies to conquer the night, claim the cities as their own, and party.

"People new to the Twin Cities are shocked that the city rolls up its streets at 9 p.m." said Steve Dietz, founding director of

A former new-media curator at the Walker, Dietz, 52, has spent the past six years organizing midsummer-night fests for San Jose, Calif. "This recognizes the kind of vitality that people from New York, Boston or L.A. are used to. There's a lot of creative energy in people here, so let's enjoy it for a night."

Festivities start at sundown Saturday (8:55 p.m.) and end at sunrise Sunday (5:28 a.m.).

The Minneapolis shindig kicks off at the Stone Arch Bridge, where from 8:55 to 9:15 p.m. composer Chris Kallmyer will lead 100-plus musicians (drums, brass, woodwinds and tin whistles) in a performance inspired by the Mississippi. Deborah Miller will project photos onto the nearby Gold Medal Flour silos and Diane Willow promises to coax a "mesmerizing glow" from bioluminescent plankton as Osman Khan throws a laser canopy over St. Anthony Falls.

Simultaneously in St. Paul -- at the Upper Landing near Shepard Road -- a "Car Horn Fanfare" coordinated by Philip Blackburn and ArtCars of Minnesota will precede a "Scattered Light" show involving more than 1,600 LEDs and regular bulbs by San Francisco-based artist Jim Campbell. Blackburn also has installed wind-harp sculptures in downtown St. Paul and plans to use the city's sewers and storm drains as a really big pipe organ.

From its berth on nearby Harriet Island, the Jonathan Padelford riverboat will play host to a "Floating Chautauqua," blending artistic and scientific presentations.

Ghost horses & sperm helmets

Other events range from high-tech sights to funky, down-home games.

Andréa Stanislav's "Nightmare" is a new video project that the University of Minnesota sculpture professor will be testing on the Mississippi near the Stone Arch Bridge, assuming the river is not too turbulent. She plans to create the illusion that a white horse is running on the water. Technically the "horse" would consist of a high-definition video image on a 10-foot-tall screen on a barge propelled by a tugboat that would disappear in the darkness.

She's been working on the project for several years and hopes eventually to run the horse the whole length of the Mississippi, from Minneapolis to New Orleans, where it would "hold a memory of Katrina as a memorial project."

"From afar -- an apartment or condo or the bluff -- you question your own eyes; did you really see this thing or not?" Stanislav mused recently. "The horse is very ghostlike, and I'm working off ideas of what a white horse means in various cultures, to Native Americans, in [the Bible's book of] Revelations and elsewhere. It's something that could be positive, a symbol of hope, but the title 'Nightmare' is also an omen of something darker."

Two other University of Minnesota art faculty members, Jenny Schmid and Ali Momeni, have cooked up an elaborate participatory light show that will play out between 10 p.m. and midnight on the exterior of the Minneapolis Institute of Arts and in adjacent Washburn Fair Oaks Park. Freshmen from Washburn High School in Minneapolis will interview and photograph the audience, then project the images and responses into translucent windows in an architectural diorama. Next, shadowy images of the visitors and the diorama -- which resembles a circular stage set of Venice -- will be projected onto the museum's facade along with drawings that Schmid and others will create on the spot.

"The event is a form of street theater, though there are no performers involved," said Momeni.

Meanwhile, back at the Stone Arch Bridge, the "Egg and Sperm" hide-and-seek game will put a whole new spin on sex education. Designed and built by Minneapolis puppeteer Janaki Ranpura, the game centers on a translucent fiberglass egg -- 8 feet in diameter and about 10 feet long -- that is propelled by a rider on an adult-sized tricycle concealed within the egg. Six pursuers wearing bicycle helmets fitted with "glowing, electro-luminescent sculpture that look like swimming sperm" go after the egg.

Looking for a sponsor

Northern Spark is a new nonprofit organization that Dietz launched with a $132,000 grant from the Minnesota State Arts Board and the state's arts-and-cultural-heritage-fund. He said the organization has raised about $90,000 more from "the usual suspects" -- that is, individuals, foundations and corporations.

"We are doing this on a shoestring compared to other comparable events," Dietz said. "But we are looking for a big sponsor."

Timing, technical wizardry and ephemeral effects set Northern Spark apart from the myriad other art festivals that jostle for attention nearly every weekend all summer. Most art festivals are merchandising ventures designed to sell handmade products on sunny streets in steamy weather. By contrast, Northern Spark, which is modeled after similar events in Paris, Toronto, St. Petersburg and other cultural capitals, is experiential and uncommercial (although food vendors will be on hand).

"This is cultural programming for a broad audience," said Dietz. "And when you do something at night, it's a very different experience and it's breathtaking, frankly. Even something as simple as being in a gallery at 2 a.m. is a heightened sensibility that is quite exciting. So I don't know if we need the event, but it is different from what has traditionally happened here, and complements without repeating anything. So, if we find an audience, that's fantastic."