But now, it has robots.

Fifty years ago the only way to view or use the collection was to walk into a reading room. Today the process can be completed online and the material gets to take a ride on a wheeled-robot affectionately called Isaac.

The library has four automated delivery robots that whiz around the cavernous lower levels of the building transporting material to and from the stacks and the reading rooms.

Stack attendant Paul Nordern said the Isaac robots cart more than 700 items around the building per day and together have had more than 40,000 operating hours.

"As far as we know we have the largest fleet of these robots in Australia," Mr Nordern said.

"And we believe we are the only library in the world using these robots."

While robots traverse the basement of the library more than half a million people visit it's upper levels each year.

The 50th anniversary marks the library moving into its home in the grand building that director-general Marie-Louise Ayres attributes a lot of it's success over the years to.

“I just love this building," Dr Ayres said. "I walk under that beautiful Tom Bass sculpture every day, and feel the sense of space and grandeur that I hope is not too scary for people.”

"Although the building is strictly classical and gosh it might have been plonked down from Greece, I think when you come into it, it's very Australian."

While the building was cleverly designed and is undoubtedly impressive, Dr Ayres said the staff and everyone who visits the library were responsible for creating such a welcoming environment.

She recalled walking into the foyer several years ago with her daughter and seeing a group of young mothers sitting together, prams parked, chatting while all breastfeeding.

"I said to my daughter, take a good look at that because you won't find that in any other national library in the world."

Dr Ayres said the library has conducted surveys which showed that people's knowledge of the library and their engagement with the collection both in person and online had continued to grow.

If she had just one hope for the institution, it's that it continues.

“I think and hope and believe that more Australians will know about the library and more importantly they know it’s their library, it’s here for them to use and they don’t have to have a PhD to use it.”

She said in 2018, the library is doing basically the same job, just in different ways.

"It’s more that why we collect hasn't changed and in some ways what we collect hasn't changed but it’s really about how we collect it that has changed a lot," Dr Ayres said.

"We say that we collect today what will be important tomorrow, and I don’t have any doubt that the people working in the library in 1968 were thinking the exact same thing."

While the library is still collecting physical items, adding around 2.5 kilometres per year, in the last financial year just over half of the material added to the collection was digital.

Dr Ayres said it was becoming more common that when the Library acquired personal archives these days they came in a hybrid form such as the recently acquired archive of former senator Bob Brown that consisted of hundreds of boxes of paper but also half a million emails.

The National Library open day will be held on Sunday from 10am to 4pm and will highlight special items from the collection, offer plenty of kids activities and food and drink is available.