BILLIE Denny is too young to understand the significance of it just yet.
But, soon she will become acutely aware of why every year on December 15 the nation stops to remember a terrible event that she was in the middle of.
The youngest survivor of 2014's Lindt siege was the unborn child of barista and former Sunshine Coast woman Harriette Denny.
The mother and daughter joined other victims of the terrorist event and high-profile Australians like Prime Minister Malcolm Turnbull at a two year anniversary memorial service at St Stephen's Uniting Church.
The service took place just around the corner from the Martin Place cafe.
Ms Denny - who was 14 weeks pregnant at the time of the hostage drama - sat up the front of the historic 1855 church along with fellow survivors Louisa Hope and her mother Robin, Jarrod Morton-Hoffman, Joel Herat, Selena Win Pe and John O'Brien.
Others in attendance included the families of fatal victims Tori Johnson and Katrina Dawson.
Mr Turnbull hugged survivors and relatives during the ceremony, where Sydneysiders from all walks of life laid flowers at a candlelit "table of payer and hope" set up at the altar of the church.
St Stephen's Reverend Ken Day said the memorial was to remember those "who survived the trauma" and "still live with painful thoughts and memories".
NSW Premier Mike Baird said the siege, where terrorist Man Monis took 18 people hostage at 9.45am on December 15, was "an event that irrevocably changed the lives of so many".
"For the families of Katrina Dawson and Tori Johnson, the day is a reminder of their terrible loss, and the tragedy of these two lives taken in such a violent way."
Work was continuing on a permanent memorial in Martin Place, Mr Baird said.
More than 110,000 floral tributes were laid in Martin Place after the incident, which were then collected and turned into compost, some of which were recently laid in the flowerbeds surrounding the Archibald Fountain in Hyde Park.
The floral tributes will also form the basis of a permanent memorial for the victims of the tragic event.
"We will continue to work closely with the designer, Professor Richard Johnson AO, and with Katrina and Tori's families to finalise the design elements of the memorial," Mr Baird said.
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