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)

People walk along a street with long-tailed macaques in Lopburi, north of Bangkok November 29, 2015. (Photo by Jorge Silva/Reuters)

A woman walks inside a building in downtown Havana, Cuba April 21, 2016. (Photo by Alexandre Meneghini/Reuters)

People are reflected in mirrors as they walk in a busy shopping district in Tokyo, Japan, December 25, 2015. (Photo by Thomas Peter/Reuters)

An enthusiast dressed as a zombie takes part in the annual Zombie Walk festival in Prague June 1, 2013. (Photo by David W. Cerny/Reuters)

A woman walks with a squirrel on her shoulder at Maeklong market at the outskirts of Bangkok, Thailand September 20, 2016. (Photo by Jorge Silva/Reuters)

Residents walk past electoral posters in Port-au-Prince, Haiti, January 28, 2017. (Photo by Andres Martinez Casares/Reuters)

People dressed as zombies take part in a “Zombie Walk” parade in Athens, Greece, February 25, 2017. (Photo by Michalis Karagiannis/Reuters)