The holder of half a dozen world records will walk across the Grand Canyon on a steel cable with nothing but the Little Colorado River 1,500 feet below on June 23. With no tethers or safety nets, the walk will be the highest tightrope attempt ever for the 34-year-old, at a height taller than the Empire State Building. Last year, Wallenda, a seventh-generation member of the “Flying Wallendas” family of acrobats, became the only person to walk a wire over the brink of Niagara Falls. Photo: Nik Wallenda walks across a tightrope 200 feet above U.S. 41 on January 29, 2013 in Sarasota, Florida. (Photo by Tim Boyles)

Two cats watch a mouse walking on the pavement in Kuwait City on March 8,2017. (Photo by Yasser Al-Zayyat/AFP Photo)

People wearing costumes walk during Halloween in Sierra Madre, California, U.S., October 31, 2017. (Photo by Mario Anzuoni/Reuters)

A woman carrying a basket of papayas while walking through a vegetable market in Bangkok, Thailand November 11, 2011. (Photo by Kerek Wongsa/Reuters)

Actress Scarlett Johansson Honored With The Star On The Hollywood Walk Of Fame on May 2, 2012 in Hollywood, California. (Photo by Jon Kopaloff/FilmMagic)

Models walk the runway at the “A Child of the Jago” fashion show during London Fashion Week at the Wilton Music Hall on September 21, 2011 in London, United Kingdom. (Photo by Ian Gavan/Getty Images)

Monks take a tiger out of its cage for an afternoon walk June 5, 2001 at the Wat Pa Luangta Bua monastery in Kanchanaburi, Thailand. (Photo by Paula Bronstein/Getty Images)