Twins Sienna and Danielle Taylor-Moore 9, said they knew a bit about Mr Sarjeant and the work he did for the arts in Whanganui.
"Today was his birthday," said Sienna.
"He looks like a movie star in his photo," said Danielle.
Restoration work on Mr Sarjeant's grave was recently undertaken by Marco Buerger of Heritage Conservation Ltd.
The ceremony was followed by morning tea at Sarjeant on the Quay and there was an afternoon lecture at the Whanganui War Memorial Centre.
The inaugural Henry Sarjeant Memorial Lecture was given by historian Jock Phillips.
The lecture focused on Mr Sarjeant's gift to the city, and the place of benefactors, philanthropy and gifting in New Zealand cultural life.