THE “controlled” explosive demolition of an obsolete, 53m concrete silo in Denmark on Friday took a turn for the worse — literally — when it toppled in the wrong direction and came crashing down on a large library building.

Hundreds of spectators at the harbour in Vordingborg gathered along the shore and aboard boats to watch the planned explosion at 4.45pm local time. Unfortunately, they also were given front-row seats to the unplanned destruction of a nearby building when the demolition went awry, the New York Post reports.

The neighbouring building was a library and cultural centre. Footage of the blast blunder was posted to YouTube on Friday and has received over 100,000 views.

No one was injured, however the egos of the demolition-project managers will have definitely seen better days. While the explosion seemed to go to plan to begin with, things soon took an unexpected turn.

“I simply do not know how it may have gone so bad,” blasting manager Kenneth Wegge said.

A photo of the aftermath shows one corner of the waterfront building reduced to a mess of splintered timber and stone, with the fallen silo just metres away.

Officials are trying to piece together what caused it to tip the wrong way despite months of planning.

“I will put my head on the block. We have prepared half a year for this,” Mr Wegge told the network.