US man set for Grand Canyon tightrope walk US daredevil Nik Wallenda hopes to make history by walking across the Grand Canyon on a tightrope. RECORD-BREAKING US daredevil Nik Wallenda hopes to make history again by walking across the Grand Canyon on a tightrope, 450 metres above ground over the world-renowned landmark. Wallenda, who was the first person to walk across the Niagara Falls last year, will be rigged up with multiple cameras and microphones broadcasting the death-defying feat live around the world. And unlike the Niagara Falls walk, the 34-year-old will wear no safety harness for the stunt, likely to take him 25 minutes in searing temperatures over the famous tourist attraction. At Niagara, Wallenda - who first walked the wire aged two - braved strong winds and heavy spray to walk on a cable suspended about 60 metres above North America's biggest waterfall, on the US-Canada border. On Sunday (local time) he will step out into the void over six times higher - a height greater than that of the Empire State Building - with nothing but a five-centimetre thick steel wire between him and the rocky canyon bottom. The walk is set to begin from around 6pm Sunday (1100 AEST Monday), an hour or two before sunset over the Grand Canyon and will be broadcast live in 219 countries by the Discovery Channel. On Saturday, organisers described conditions at the walk site, in a remote area at the eastern end of the Canyon, as "very windy." Wallenda has been planning the walk for about four years, homing in on a remote location at the eastern end of the mighty geological chasm, on land operated by the Navajo Nation Parks and Recreation. He began final training in Florida weeks ago, boosting stamina by walking repeatedly along a 300 metre long rope, and using wind machines to simulate gusts of up to 80 kilometres an hour. Sunday's walk across 365 metres of rope could potentially be delayed in the unlikely event of winds of above 70km per hour, or if there was a risk of lightning. A new attempt could then be made the following day. There will be a seven to 10-second delay on the live broadcast. Wallenda, a seventh generation member of the Flying Wallendas circus family, said that as he steps out he would be thinking of his great-grandfather Karl Wallenda, who died in 1978 after falling from a tightrope. He has trained for the worst, and said that - unlike his great-grandfather, who had an injured collarbone and double hernia, and grabbed vainly for the wire before falling to his death - he would be able to hold on if necessary. That help would be in the form of rescue trolleys, which hang underneath the cable and could be rolled out in seconds on a winch system to Wallenda, clinging on for his life.