Casey Anthony Did Not Appear at Caylee's Birthday Memorial

Amidst a sea of violet balloons, hundreds gathered to commemorate what would have been Caylee Anthony's sixth birthday. Among the gatherers, stood the people who perhaps knew her best: Caylee's grandparents, George and Cindy Anthony.

They mingled, murmuring words of thanks and appreciation Tuesday evening as the densely packed crowd clamored for hugs and a chance to show their support. They gathered at the site where Caylee's skeletal remains were found three years ago.

Caylee's mother, Casey Anthony, remains in hiding following her acquittal of murder charges in Caylee's death.

For the elder Anthonys', the grief is still fresh.

"It's hard to come down here," said George Anthony, sobbing. "It's hard."

A march organizer spoke to the crowd saying, "We want the Anthonys' to know that we back them, we support them and we feel the pain of losing little Caylee. She was our little adopted daughter here in Orlando. All these little kids that come out here, that was their little sister. And so, we're so proud of them for coming here."

Casey Anthony Does Not Appear for Daughter's Sixth Birthday Memorial

The crowd marched together, some hand in hand. They said a prayer and, in unison, released a torrent of balloons into the sky. Cindy Anthony released a butterfly, a symbol, she said, for Caylee.

As they marched back, Cindy and George Anthony shared a hug and the crowd broke into the birthday song.

The site at which they gathered is soon to turn into a memorial for the slain toddler. A non-profit organization, Bring Kids Home, just released the design for the planned Caylee Anthony Project.

"It was kind of a garbage area," said Eric Segura, spokesman for Bring Kids Home. "After a couple of years of waiting and watching we decided to do something."

The project will be a walkway near the site where Caylee's remains were found and is estimated to cost $200,000. They are asking for $25,000 in public donations and are continually seeking partners to help alleviate costs. All workers are volunteers and none of the money goes towards salaries.

This project is not affiliated with the foundation that George and Cindy Anthony were supposed to start on Tuesday for their granddaughter called Caylee's Fund. ABC News tried to contact their lawyer for comment but he did not immediately respond to inquiries.