Four decades after a bomb blast ripped through a Sydney street, the city will pause to remember the lives lost and reflect on how one of Australia's first tastes of terror changed the nation.
Garbage collectors Alex Carter and Arthur Favell were killed when a bomb, hidden in a rubbish bin, was loaded into their truck's compactor outside the Hilton Hotel on February 13, 1978.
Police officer Paul Burmistriw was guarding the entrance of the hotel when he was mortally wounded.
He died from his injuries nine days later.
The assumed targets were then prime minister Malcolm Fraser and 11 visiting heads of state who were staying at the hotel for a Commonwealth Heads of Government Meeting.
The bombing triggered numerous conspiracy theories as suspects from a Hindu sect, Ananda Marga, were implicated, charged and cleared in the following years.
To this day the identity of the culprit behind the attacks remains a mystery.
The 40th anniversary memorial will be held at the Hilton on Tuesday morning with dignitaries including NSW Police Minister Troy Grant and Police Commissioner Mick Fuller pausing to reflect alongside bomb victim retired senior constable Terry Griffiths.
Police Association of NSW president Scott Weber said Constable Burmistriw's death was "a horrible and stark reminder of the inherent dangers and risks involved in police work".
"Constable Burmistriw paid the ultimate sacrifice," he told AAP in a statement on Monday.
"Losing a member of the police family is always difficult, the Burmistriw family are not alone in remembering that awful day or their loss, the thoughts and prayers of police officers across the country will be with them."
Sydney Lord Mayor Clover Moore, speaking at the 30th anniversary memorial 10 years ago, said the bombing had been a "shocking jolt" which thrust Australians into a world that was less safe and comfortable than before.
"For the families (of those killed) that jolt was experienced at a far more visceral level," Ms Moore said.
"Each of them lost a husband, a father, a son or a brother - their friends lost a mate who would never be replaced."