'But when we are nostalgic we take pictures," wrote the late Susan Sontag in her seminal 1977 monograph On Photography, and nostalgia is certainly a defining element in the latest work of Sontag's longtime partner, Annie Leibovitz.

Perhaps the photographer with the highest name recognition working in the world today, Leibovitz is famous for her baroque-styled Vanity Fair covers and celebrity portraits. She began her career more than 30 years ago, working for Rolling Stone magazine, when it was still a publication that set trends, influenced issues and had its hand on the pulse of US youth culture.

In recent years, after the death of Sontag and a lawsuit resulting from her less-than-careful financial dealings, Leibovitz has continued to play a major role through her portraiture in defining the images that we see of celebrity and people in power. But her new book, Pilgrimages, suggests that she also has had a personal need to escape from the restrictions which her own celebrity has imposed on her.

As she told the New York Times in a recent interview: "I needed to save myself. I needed to remind myself of what I like to do, what I can do."

So instead of putting together a book of some of her better-known photos, which may have guaranteed her some money, Leibovitz chose instead to do something else - a personal book that everyone told her wouldn't make her any money but which she needed to do. Originally she and Sontag had made a list of places they would visit for another book, but with the death of Sontag in 2004, that idea changed - now Leibovitz would travel to places on her own list.

A journey to several places that have no connection to each other besides Leibovitz's personal relationship to them, Pilgrimages is unusual for Leibovitz insofar as there are no people in its pages.

Rather, we are given a photographic portrait of nostalgia through natural-light digital photographs of artifacts and mementos of a range of historical subjects, from writers Emily Dickinson, Ralph Waldo Emerson and Louisa May Alcott to naturalist Charles Darwin, photographer Ansel Adams and artist Georgia O'Keeffe. Even Elvis makes an appearance. Through explanations of the personal significance of these places and captions, Leibovitz tries to show readers why she chose the places she did and the objects she has photographed.

As she told The New York Times: "You don't ever get away from people, really. These are pictures of people to me. It's all we have left to represent them."

The question, however, is this: can someone whose known body of work is so highly stylised simply snap pictures of things and expect us to react with awe - based on her reputation - to images that are sometimes unimpressive and perplexing rather than profound?

That's not to say that there is not a fair share of beautiful pictures here. The detail of Dickinson's only surviving dress; the old Victorian charm of Freud's couch; a television with a bullet hole in it showing two of The King of Rock and Roll's favourite pastimes; a postcard with a heart drawn on it pierced by the bullet of Annie Oakley; Robert Smithson's once submerged, now visible Spiral Jetty earthwork sculpture in Utah - these images have a nostalgic beauty encapsulated in that brief moment between Leibovitz's eyes resting upon them and her finger pushing the shutter.

But there is also a slew of pictures that at first seem to do no more than reaffirm another of Sontag's assertions about the medium, the one which says: "Photographed images do not seem to be statements about the world so much as pieces of it, miniatures of reality that anyone can make or acquire." Pictures that anyone could have taken.

But these images also allow space for readers to make their own decisions about their feelings towards Leibovitz's heroes, because it's the space between execution and impression that makes for lasting work in all mediums. For if you're not given a chance to exercise your own abilities of interpretation, then why should you care?

As receivers, audiences are a fundamental part of the process of what has made photography not just a medium for recording memory but also one that says something about the world and the people who have influenced it.

Taken as a statement about what it takes to make pioneers in the world, and as a comment on the difficulties and importance of sticking to your ideals, all the photos in the book together present a portrait of Leibovitz in her own inimitable way, working in the format she knows best, as a person who is, like the celebrities she has spent so many years capturing, more than the sum of her work - she is also a pioneer, a mother, a person interested in history and memory and the idea of legacy.

If artists don't change and progress in their work as they do in their lives, then they lack what is needed to transform them from people of the moment into people with vision and ability outside the boundaries of time and space.

When someone in the future goes looking for the remains of Leibovitz's legacy, they will find more about her in the pages of Pilgrimages than on the covers of Rolling Stone and Vanity Fair.

But they will also need those pop culture images to realise the power of Pilgrimages - images that illustrate the paradoxical reality of trying to be true to oneself despite being labelled with the dreadful "household name" tag.

• Pilgrimages is published by Jonathan Cape, R570