The great chronicler of our city, the recently departed Keith Dunstan, once wrote that while Spring Street has more nobility, Flemington Road more grandness and Alexandra Avenue ''all those lovely vistas of the Yarra'', the essence of Melbourne is in Collins Street. He was unquestionably right, although I would probably put St Kilda Road ahead of Flemington Road in any discussion of our grandest boulevard. But there is no argument over the street named after the former lieutenant-governor David Collins. It's undoubtedly our premier street. In fact, I'd go further - I'd argue it is Australia's best and should be celebrated accordingly. I'm not the first person to make this claim. Historian Judith Buckrich penned a splendid book in 2005, simply titled Collins and boasting that it was ''the story of Australia's premier street''. She'll get no argument from me. So why isn't Collins Street marketed as such? We are forever touting our graffiti-strewn laneways, but I cannot recall a single campaign that invited interstate or international tourists to simply walk the country's best street. And what a walk it is. Another of the great voices of Melbourne, the former ABC broadcaster Douglas Aiton, recently recalled how a family friend would visit from Brisbane just to experience his favourite street. ''Walk down Collins Street,'' the Queensland visitor would say, ''and feel like a king.''

Like the rest of the streets running parallel to the Yarra on Robert Hoddle's famous grid, Collins is a mile long. Or thereabouts. Which means it can easily be walked in 15 to 20 minutes, unless you've stopped at the Melbourne Club or the Collins Place food court across the road. Collins Place is not my favourite part of the street, even though the world-renowned I.M.Pei helped design it. Still, it's better than some of the buildings directly opposite. The walk is best done slowly. Really. Slowly. I recently did it for the first time in years, starting at No.1, on the southern side of the street where it meets Spring, and heading all the way down to Media House, home of The Age. (I didn't bother with the so-called ''extension'' - I wish they'd given it another name, in fact.) Then I crossed over and ambled along the northern side, until I was back at Spring Street, standing outside the heritage-listed Alcaston House. With stops along the way and one or two coffees, it took me two hours.

But I could have easily stretched it to half a day, longer if I had taken in a show at the Regent or the Athenaeum theatres, or stopped to buy a bauble at Tiffany. On second thought, make that a truffle at one of the chocolate outlets that seem to be springing up everywhere. Melburnians have always loved the stretch between Elizabeth and Swanston on Collins' northern side, and the throng is still thickest there. In her book, Buckrich recalls how thousands upon thousands would flock into the city on a Saturday morning to ''do the block'', promenading up and down in their finest. I prefer the quieter easterly reaches, up the hill, past the Town Hall and the churches - Collins Street Baptist, Scots' and St Michael's. But I want to use my last weekly column for The Sunday Age - a new project demands all my time - to issue a plea: can Planning Minister Matthew Guy and his development-mad colleagues and cronies please leave the street alone. We came dangerously close to destroying it in the 1960s when the similarly gung-ho government of Henry Bolte laid waste to some of its most beautiful elements. Only far-sighted activists and building unions saved it from destruction. We must never allow it to be threatened again. Finally, thanks to all those readers who have indulged me with their attention, opinions and feedback, good and bad, over the past three years. It's been an honour and a privilege to contribute to a masthead I helped launch almost a quarter of a century ago. ■

Bruce Guthrie is a former editor of The Age and The Sunday Age. This is his final weekly column.