It's been 43 years since the first reported case of HIV, and advocates say there is still more work to be done.
Vince Cristostomo, who was diagnosed at 28 years old and told he wouldn't live past 30, is now 63.
"It's amazing how far we've come and how far we haven't," he said.
Dan Bernal added, "at 54, I'm so grateful to have a career I love and to be planning for retirement."
The National AIDS Memorial in San Francisco played a key role in this day of reflection.
"This healing garden allows us to remember and magnify hope," said John Cunningham, the CEO of the National AIDS Memorial.
While medical advances like PrEP have made progress, he emphasized the need to tackle stigma and discrimination.
Vince, who visited a tree planted for his partner, Jesse, said, "if I knew then what I know now, I'd have made different choices."
Despite progress, HIV still disproportionately affects Black, Brown, and transgender communities.
World AIDS Day reminds us of what was and what is possible.
For more information on the National AIDS Memorial, visit aidsmemorial.org