Few can begin to comprehend what the Sydney siege's 17 hostages went through in their hours of captivity, but Madeleine Pulver may know better than most.

The hoax collar bomb victim, who was held hostage in her Mosman home by a balaclava-clad intruder in 2011, spent a short time in Martin Place on Thursday morning, accompanied by her mother.

"It's horrible," she told Fairfax Media as she fought back tears.

"I mean, you can't compare, two people have died out of this. You can't compare the situation I was in to this, it's just awful."

Her mother said Miss Pulver, who was 18 at the time of her 10-hour ordeal, had made the effort to pay her respects "to let them know she knew exactly how they all felt."

They placed a small bouquet of flowers next to the tens of thousands of other posies in the sea of messages, ribbons and blooms.

"I know that a lot of people were very supportive of me, so I know how it feels to feel the love. It's terrible for this to happen, it's just awful," said Miss Pulver.

"My condolences go out to the family and everyone who knew anyone who was in the cafe that day. It's just horrible."

Three people including gunman Man Horan Monis died in the Lindt Cafe siege on Monday. Sixteen hostages escaped with their lives.

Also present at the ever-swelling floral tribute was Senator Jacqui Lambie and earlier on Thursday, Premier Mike Baird paid his respect, taking time to speak with and embrace distressed mourners.