Particular highlights were the Assembly Hall, with Geoff Fuller's mural of women through the ages, the swimming pool and the gymnasium.
The school's third principal, Jill Davidson, said Ms Miller would "pop in" once a month, and retained an interest in the school until her death at the age of 101.
At her funeral, current principal Geraldine Travers had delivered a eulogy for the woman who believed in the "goodness of people".
She was said to have had "old-fashioned" qualities, charm and a "gracious, lady-like demeanour" which she impressed upon her students.
Succeeding Ms Miller at the beginning of the 1968 school year was Jean Kelt.
Miss Kelt was no stranger to the school - she had been the head girl of Hastings High School in 1937, and was a foundation staff member while Ms Miller was principal.
During her tenure until 1984, there were huge developments to the school including extensions to many of the main blocks and the building of the Music Suite and AV Room.
Miss Kelt died in 2011, the day after she turned 91. The school said her legacy was immortalised in the school's technology block and a Year 9 sport scholarship that bears her name. In a eulogy also delivered by Ms Travers at Miss Kelt's funeral, her demeanour and values were said to be woven into the school's lasting character.
When Jill Davidson moved into the role in 1984, she had been deputy principal for almost a year.
She said one of her proudest achievements was the growth the school underwent while she was principal.
"The school enrolments went from about 600 to 1000 in the first few years," she said.
"It became the largest school in Hawke's Bay for a while."
A low point was when Flaxmere Intermediate turned into a college in the early 1990s, and the school was threatened with closure.
"We had to fight," Ms Davidson said. "We said we may get smaller but there is no need to close us down.
"Parents were paying for girls to come in on the bus because they believed in the ethos of the school."
During her 13 years as principal, Ms Davidson oversaw the refurbishment of most school buildings, and did "anything to help staff and students to develop to their full potential".
"I was an educator," she said. "I had ideas of where schools should go and I was able to develop those."
She also introduced "non-streaming" to the school so none of her students felt disadvantaged.
Ms Davidson left the school in 1997 to pursue a medical interest, and now works as an acupuncturist.
Since then she said there had been a lot of new development within the school.
"But what fascinates me is to see the things we brought in to the school that are still continuing, the ideas we brought in are still there."
The school's current and longest-standing principal, Geraldine Travers, arrived at the school in 1998.
When she was welcomed to the school in 1997 she brought with her some students from the school she was principal of at the time.
"They regaled me with a list of what I had to do," she said, which included changing the space, painting buildings and improving aspects of the school's appearance.
"It was a daunting list but I loved that it came from the students."
In her 18 years, Ms Traveres said she had accomplished this list "and then some".
In her time there has been a major technology upgrade, and the building of a new cafeteria with a substantial shaded area for the girls to sit and enjoy their breaks.
She was also responsible for the building of a Student Centre, including a dedicated area for international students.
"There's hardly been a part of school that has not been attacked in some way," she said.
"We attacked the physical environment by making the place warm and welcoming."
It wasn't just the buildings that Ms Traveres said had changed during her tenure.
The school's curriculum had changed with multiple pathways made possible by NCEA, which meant there were now many ways students could achieve.
As a nearly digital school, their students had access to technology "you never thought schools would take for granted".
"We have 3D printers, laser-cutters," she said.
"We're preparing our girls for life in this world."
A highlight was being named the best state secondary school in the country by North and South magazine.
"In my professional career that was my proudest moment," she said.
Another change she was proud of was the number of girls who were finishing their five years at the school.
"People used to say secondary school was a triangle, because you had a broad base because students came in and as the year levels progressed girls would get picked off until it was just people wanting to go to university.
"Now the school has changed to one with straight sides," she said.
"It's so good for society to have better educated women.
"They are the mothers of the nation so their children will be well educated, too."
When the school celebrates its 60th anniversary on Tuesday, Ms Traveres said the "coolest thing" would be the opportunity for former students to return to see how everything had changed.
