NEW : Other daredevils have tried their luck , but farther downstream . Next on his to-do list ? The Grand Canyon . Comment: His great-grandfather was killed at the age of 73 attempting to walk between two buildings .
NEW : Other daredevils have tried their luck , but farther downstream . Next on his to-do list ? The Grand Canyon . Wallenda had a near fall after stumbling on a tightrope above Baltimore 's Inner Harbor . His great-grandfather was killed at the age of 73 attempting to walk between two buildings .