hes the worlds tallest man alive, but not ever. there was an american who reached 8'11"
http://www.worldslargestthings.com/easterntour/wadlow.htm,
this guy
http://news.independent.co.uk/people/profiles/article315630.ece
but the tallest ever reached somthin like 11'3". people say its hard to tell how tall he really was, because it was a loooong time ago and conversions could make him anywhere from 9.5-over 11 ft. but the best estimate has been somewhere right around 11'3"