I ran the Christchurch marathon at the weekend and it winds you around pretty Hagley Park, through the CBD and then out into some of the red zone suburbs.

The red zone is always confronting. You can see where houses once stood because although the fences are gone, the trees and shrubs that were once planted along their borders are still there. They still act as a border of sorts, revealing where a house once stood, except there is no house, no fence. No anything really.

And while that is confronting, this time I found the CBD more confronting. It was a cold, grey, bleak day on Sunday, and for some reason that made the number of derelict buildings stand out even more. There is some truly beautiful commercial real estate in Christchurch now, but the beauty and life is often sucked out of it by ramshackle and abandoned buildings.

The windows are broken or bordered up with ply wood. There's graffiti everywhere. Orange plastic bollards are everywhere, weeds are sometimes shoulder-height and wire netting fences keep pedestrians away.

If you live in the city, I can see why you'd keep out of the CBD. It's so important to get people back in there, but I can see why you wouldn't go. It's ugly. It's depressing. It reminds you of a time which was traumatic and tragic, and while it's important to remember that time, you don't need to see it daily. You don't need to be reminded of what happened six years ago by walking past so many cracked and broken buildings.

I know the Christchurch council says it's going after the so-called "Dirty 30" building owners - they're targeting the most obvious 30 or so derelict properties that are holding up the city's rebuild. And they should go after them -- and hard. It's an eyesore. This once beautiful city is slowly getting to its feet, but it's being held up by those who'd taken their insurance pay outs and then done nothing.

I was in Christchurch with about 25 people who were all there for the marathon. Myself and a couple of others were native Cantabs, but most were what I would call domestic tourists. Just in Christchurch for the long weekend. And all were staggered at the buildings and the devastation they saw around them as they ran.

And quite about from the aesthetics of it all, I do wonder how it affects your mind and your mental health if you live in Christchurch, and every day you see buildings that are broken, the facade has collapsed, one floor has pan-caked into another, the windows are smashed or boarded up, or the weeds are out of control. It must remind you every day of what occurred some years ago now. And how does that help you move on?

There are big chunks of the CBD that remain in a post-disaster state, and building owners and the council need to work together - and fast - to remedy that for the sake of the city, and its people.