[1][2] Brandenberg was born in Wildwood Crest, New Jersey, to James Peter and Stella (née Lagakos) Liacouras.
Her parents, who lived in Philadelphia, were originally from Greece, and they taught her to speak Greek as a first language.
She then moved back to Philadelphia and worked as a freelance artist, creating art for advertising and display purposes.
After moving to Franz's native Switzerland, Brandenberg wrote her first book, The Story of William Tell, about the legendary Swiss archer.
Brandenberg's career as an author and illustrator led her to explore many subjects of historic and scientific interest.