Hundreds of people watched the demolition of the quake-damaged Radio Network House in Christchurch on Sunday morning.
A four-metre-high pile of rubble is all that is left of the 14-storey building after the first demolition by implosion of a building in the country.
After the crowd counted down from 10, the high-rise was reduced to rubble in less than eight seconds.
About eight loud blasts went off before the facade began to slip off, and the building then collapsed inwards in a pall of dust.
One of the co-owners of the building, Greg Hedges, says he is sad to see it come down, but glad the demolition went to plan. "It was magnificent the way it went down," he says.
Six-year-old boy set it off
The right to detonate the unsafe building was auctioned off on Trade Me and won with a bid of $26,000 by a group of eight demolition companies.
They offered it to the Child Cancer Foundation, which nominated six-year-old Queenstown boy Jayden Halliwell, who is currently being treated for kidney cancer.
Controlled Demolitions, the American company contracted to do the implosion, says the procedure worked even better than planned, and more quake-damaged buildings should be demolished with explosives.
Company president Mark Loizeaux says none of the buildings nearby were damaged, and the seismic effect of the explosives was minimal.
Mr Loizeaux says he surveyed a dozen structures in the city after the February 2011 earthquake and he believes at least half of those would have been suitable for demolition by implosion.
He says it is an efficient process that would allow streets surrounding hazardous buildings in Christchurch to be reopened sooner.