Daredevil Nik Wallenda's unprecedented Niagara Falls tightrope walk to air live on ABC Friday, June 15

"Countdown to Niagara: The Greatest Megastunts of All Time" airs at 8 p.m.

"Megastunts: Highwire Over Niagara Falls - Live!" airs 9 to 11 p.m.

On June 15, Nik Wallenda will walk approximately 1,550 feet on a tightrope wire, suspended 173 feet above the raging waters of Niagara Falls - an unprecedented feat that has been banned for more than 125 years. ABC will air Wallenda's long-planned stunt live. The "Megastunts" ABC special will be part of a two-part, three-hour event that will include an hour devoted to the greatest stunts in history and culminate in Wallenda's walk.

Anchored by Josh Elliott and ESPN's Hannah Storm, and featuring reporting from Elliott, Storm, Bill Weir and Sam Champion, "Countdown to Niagara: The Greatest Megastunts of All Time" (8 p.m.) and "Megastunts: Highwire Over Niagara Falls - Live!" (9 to 11 p.m.) air Friday, June 15, on ABC (WKBW Channel 7 in Western New York).

Wallenda's tightrope walk over the Horseshoe Falls, the biggest of the three falls that make up Niagara Falls, is unprecedented and will be a culmination of a life's work for Wallenda, 33, and his entire daredevil family.

"It's very exciting. This is something I've wanted to do for a long time," said Wallenda, a seventh-generation member of the legendary Great Wallendas, a traveling family circus troupe dating back to 1780. "It's been a dream I've had since I was 6 years old when I first visited the falls with my parents. I remember looking across ... and thinking, it would be cool to be the first person in the world to do this."

Crossing the Niagara River on a tightrope has been banned since 1890. Thirteen tightrope artists have traversed the gorge throughout history, notably the Great Blondin, but Wallenda discovered in his research that no tightrope artist had ever before walked directly over the awesome and raging cascades.

WALLENDA WIRE STRINGING

WATCH:

• Top Stunts Countdown: Sneak Preview - Nik Wallenda's great-grandfather did headstands over gorge

• Watch Nik Wallenda practice for his high-wire walk across Niagara, Fri., 8 p.m.

PHOTOS:

• The World's Greatest Stunts

STORY:

• Walk Across Niagara: By the Numbers

BLOGS:

• Vote: What's Your Favorite Stunt?

• Before the Niagara Walk: Nik Wallenda's Biggest Challenge