Sitting opposite me the sculptor Sir Anthony Caro could be mistaken, perhaps, for an ordinary elderly man, with his clipped white beard and traditional tweed suit. You wouldn't necessarily think that he has created, and is continuing to create, groundbreaking sculpture. His pieces, often gargantuan in scale, can tower over a spectator while at the same time inviting you to explore, to interact with them. His vast body of work is included in galleries around the world and in the collections of the Tate and the Fitzwilliam. Yet here he was, talking to me over a large cup of tea in the North London studio he shares with his wife, Sheila Girling.

Caro was a revolutionary young sculptor, taking his pieces off their plinths and bringing them down to a more human level. But he started by reading Engineering at Christ's college ("the less said about that, the better"), going on to work for Henry Moore and then on to teaching at St Martin's, where his illustrious role-call of students included Gilbert & George, Richard Deacon and Richard Long. "I taught a lot of people... many of them have gone in totally different directions. But they all take sculpture seriously. And I hope they question the assumptions of what sculpture is meant to be."

Talking to Caro, it becomes clear he dislikes any sense of a status quo - "what ‘Daddy' tells us to be right" - and, especially, any belief in sculpture as a "monument": "My work is like the intimacy of two people talking to each other." People might find it odd, then, that the young rebel and inspirational teacher has seemingly turned into the respectable Senior Academician at the Royal Academy of Art, and that his current major project since 1999 has been to restore a bombed-out church in the little town of Bourbourg, twelve miles east of Calais.

However, Sir Anthony does not seem to have mellowed with age. He has not stopped questioning, indeed hammering at, the authorities - whether the Royal Academy, or the French church. The Chapel of Light in the Church of Saint Jean-Baptiste is unlike anything you will ever see in an ordinary church. Two massive, curved oak towers flank the choir, while the Creation theme is created in the Chapel's abstract niches and through two sculptures either side of the nave. The steel and terracotta sculptures are magnificent in their brutality - even half-finished, in the surroundings of Caro's studio, they leapt out, demanding attention. Typically, Caro hopes that the Chapel will become an open, welcoming place where people of any denomination can go to rest, to think, rather than just exclusively a place to pray - again bringing his work back down to the human scale, reasserting his belief that "sculpture is very much to do with the body. It's physical, it's to do with our size, our height, our stretch."

Even as a recently-appointed Academician, in the institution where he once learnt as a young student from archaic, brown casts of classical sculptures, Caro has caused a stir with his refusal to conform to any sense of authority. Standing up against some of the more questionable pieces included in the Royal Academy's collection, Caro told me that he has come across an odd sea-change in the way that the art world responds to new sculptors, and particularly certain artists' reliance on shock tactics: "You must keep culture moving. You can sound like an old fogey if you complain about the stuff that is shown. But, recently when I became an Academician I did complain. When I was younger the RA was the stronghold of reactionary art - now it is the other way, it's just fashionable. When I complained all these old buffers with white hair got up and exclaimed that "you must keep up with the times." But you must not if it's bad art...Modern art often has been shocking. But in the olden days, the Establishment was always on the side of being shocked, and now they are determined not to be. The wilder you are the more acceptable it is. I think the Tate Modern is going to look very silly in a hundred years time. People will look at it and just laugh. But you can't tell. Old people have always said this, and are frightened of saying it - they thought Picasso was complete nonsense."

However, in many ways Caro's work can also be shocking: he has been known to use large slabs of industrial materials (such as rusted steel and bronze) and put them at odd, jarring angles or upside down; in ways that they were not intended to be. He has also worked with ceramicists and paper-makers, creating both small-scale and large-scale art. His work appears outside as well as inside, dominating the landscape wherever they are placed, be it the courtyard to the RA or a niche in a twelfth-century church. Though he claims to be "a very bad maker, hopeless," and relies on others such as Patrick Cunningham (who has been with Caro since 1969) to work out the practical intricacies of engineering, this has helped him have a fresh, uncluttered eye when it comes to making sculpture. Unshackled by practical constraints, Caro starts with an idea, and then works with what is in front of him. As he explained to me: "[the materials] begin to speak to me."

Hearing him talk, it is obvious that his work really is his life - "You do not have hobbies if you do art." An extraordinary drive has got him where he is today, coupled with a belief that art "is much better when it stays in an uncomfortable situation, not hallowed in any way. As soon as it gets the Colgate ring of confidence we are in trouble. It wants to be up for revolution, for change." Somehow, it is not hard to believe that Caro will continue for a while yet to lead that revolution.