The 2001 event, caught live on television news channels, was voted to be more memorable than the first televised landing on the Moon and the fall of the Berlin Wall.
Princess Diana’s funeral 10 years ago took second place in the poll, followed by Neil Armstrong’s historic lunar landing in 1969 and the destruction of the Berlin Wall 20 years later.
The moment Bob Geldof urged 1.5 billion viewers to "give us your f—— money" at a Live Aid concert to raise funds for famine relief in Ethiopia came fifth in the survey of 2,000 viewers on behalf of digital TV service Freeview.
The Two Ronnies’ famous "Four Candles" comedy sketch was sixth, followed by the dance performed by Ricky Gervais in his role as manager David Brent in "The Office."
Monty Python’s "Dead Parrot" sketch was eighth, while England’s World Cup football win in 1966 was the highest-placed sporting moment in ninth place.
The assassination of U.S. President John F. Kennedy by a gunman in Dallas, Texas, in 1963 was in 10th place.
The poll was carried out as Whitehaven in Cumbria prepared to become the first place this week to switch off the terrestrial television signal in the run-up to a national switchover to digital.