When it comes to designing the family rooms for major exhibitions at the National Gallery, the possibilities are manifold, and the latest blockbuster, Gold and the Incas, has proved particularly rich.

A massive jigsaw Machu Picchu wall, feathered masks and dress-up capes, an art-lined tunnel, specially made iPad games and plenty of gold paper to make face ornaments - it's clear that someone has had plenty of fun devising ways of entertaining children while their parents soak up the treasures of ancient Peru outside.

And there's even a storybook to go with the show, about a boy's holiday odyssey through Peru with his grandmother.

Author Suzie Campbell, who co-wrote the book with her sister Jane Glasson, said writing a children's book had been a long-held ambition.

The former marketing manager at the National Portrait Gallery was speaking at the book's launch on Thursday, an event attended by a gaggle of excited children decked out in gold paper and cloaks. ''[Jane] studied early childhood education, so she's been involved with little people for a very long time and I've been involved with books for a very long time, and the material was so exciting to work with - we learnt so much about Peru,'' she said.

''I think at one stage we had Granny getting wet in Paracas, but of course it never rains, so it wouldn't have worked! It's been great fun.''

Head of access and learning Katie Russell admitted that she and her team always had an enormous amount of fun when planning the family room for each big show, although the tradition only dates back to the Degas exhibition in 2008.

But the Incas room has been by the most ambitious so far, mainly because the room is more than double the size of that occupied by the family room during the winter exhibition Turner from the Tate.

''When people come in here they feel like they're walking into the Andes,'' she said.

''I think the concept of the family room is such a great thing and the public respond to it so well. It brings the exhibition to life for children, and they go back into the exhibition with a whole lot of knowledge about how these things were made or why they're important, and that means that the exhibition experience is all the more rich.''

She said the Inca room was designed to appeal to children aged three to 12, but anyone ''young at heart'' would get a kick out of it.

■ Gold and the Incas: Lost Worlds of Peru is on at the National Gallery of Australia until April 21.

I Went With My Granny to a Place Called Peru, by Suzie Campbell and Jane Glasson, is available at the National Gallery shop.