As students and staff of UCD began a new term, they remembered victims of the Berkeley tragedy who would not be returning to college this year.
The O'Reilly Hall was full to capacity with families and friends of those who were killed and injured in the balcony collapse.
Three of the students who died - Niccolai Schuster, Eimear Walsh and Lorcan Miller - had attended UCD.
Three bound copies of the university's online book of condolence, which had almost 20,000 signatures, were presented to each of their families and a commemorative bench was unveiled in the university's Rose Garden.
"This garden is permanently open and you are most welcome to visit, contemplate and to remember your friends and your loved ones," said UCD president Professor Andrew Deeks.
Kevin O'Malley, the US Ambassador to Ireland, said the six victims and the date will also be remembered.
"We also acknowledge the tragedy of what will never be," he said.
UCD Chaplin Fr John McNerney recalled being in Oakland, California, and seeing how severely injured students in hospital had to watch the funerals of their friends on the internet to say their final goodbyes.
"It brought tears to our eyes and broke our hearts," he added.