Great, vibrant cities are mongrel entities. They grow organically. They are often a cacophony of voices. They are surprising. They are exciting. They are sometimes ugly.

Created capitals, on the other hand, are initially manicured and unsurprising.

There is, no doubt, a place for architects - but they tend to like order. They have "concepts". They appreciate vistas - and vistas are great for tourists (and architectural awards) but terrible for inhabitants, because they involve distance.

Great cities are walkable. Public transport is pervasive. You don't need a car to live in a great city.

The residents of Brasilia and Washington D.C. know this. The postcard views are terrific. The museums are marvelous - but the vibrant life happens elsewhere.

Washington has been around long enough to develop this diverse culture. After all, it produced Duke Ellington, Marvin Gaye and the great chanteuse Eva Cassidy (though only Cassidy made her career there, and was famous only after she died).

The Washington of fly-in-fly-out politicians and their helpers does remain, but there's also another, exciting D.C., of singers and arguers and livers of life.

From Mondays to Fridays, politicos speak their speeches, drink their drinks and squeeze their squeezes - but bigger, glorious life continues seven days a week, away from the picturesque centre.

These thoughts of mine are prompted by the plan to extend Canberra's light rail south from Civic.

The extension will need two different means of powering the trains - an invisible one from Civic across the eponymous lake, and then overhead power lines for the rest of the route. This more expensive option is to preserve the vision of the wife-and-husband team made up of Marion Mahony Griffin and her spouse who somehow gets all the credit.

But maybe it's time for the city to quietly move away from the vision: revere what the Griffins conceived, but don't be slaves to it.

Perhaps some hypocrisy is needed: just as China reveres Mao as it undoes Maoism, perhaps Canberra should give lip service to the grand vision but not stick rigidly to it.

Would overhead power lines on the bridge over the lake be so bad?

Nobody is suggesting ditching the vision completely. There are no plans for a McDonald's on Anzac Parade.

But a quiet relaxation of regulations would help the city grow and morph into greatness.