A picture of Ashling Murphy in her graduation robes was projected on a Trinity College building as landmarks across the country were lit up to mark St Brigid's Day 2022.
The event, organised by the group Herstory, is a celebration of women who have contributed to Irish society and culture.
In poignant scenes at Trinity College on Monday night, a minute's silence was observed for Ashling Murphy, the primary school teacher who was killed last month
A man has appeared in Tullamore District Court charged with Ashling's murder.
From next year St Brigid's Day, which falls on February 1, will be a public holiday, the first to be named after a woman.
The day marks the beginning of spring and the Celtic festival of Imbolc.
The event kicked off on Monday evening, when 100s of people gathered to mark the launch at Trinity College in Dublin.
Trinity College, the GPO and Kildare Cathedral are among the landmarks that will be illuminated over Monday and Tuesday.
Earlier this year, it was announced that St Brigid's Day had been chosen as a new bank holiday from 2023, following years of campaigning by Herstory.
The group teamed up with Irish Second-Level Students' Union to highlight the issues closest to young people's hearts, which included climate action, girl's education, mental health, racism, migrants rights and preserving indigenous cultures.
"Never before in history have young people risen up together on this scale across the world.
"Power to students as they lead the light," Herstory chief executive creative director Melanie Lynch said.
Saoirse Exton, ISSU equality officer said: "Student voice is the key to creating a better world for all, and pulling down outdated systems that threaten our very existence on this planet.
"Young people are the leaders, educators, lawyers, factory-workers, programmers, artists, legislators and so many other things, of the future and by right of our existence we must voice our concerns and the specific issues that affect us.
"By celebrating those that came before and continue to work towards dismantling the system and creating a better world, we are creating spaces for the activists of tomorrow and inviting more young people to join every fight - from climate to reproductive justice."
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