"We have always had this idea in our mind about the repair of Queen St back to its original mercantile form, which was not that old," says Johnston.
"You only have to look at photos around the early 70s before Queen Elizabeth Square was built to see the mercantile form of lower Queen St, which was a series of retailers all the way down to Quay St."
Johnston says he doesn't think there is another project around with such power to transform the city for the better.
Not only does it provide a connection between ferries, trains and buses, including a new bus interchange on Albert St, but a seamless connection along the waterfront that is missing at the moment, he says.
"Ultimately, that waterfront stretch from Wynyard, the Viaduct, Commercial Bay, Britomart, that's an experience that could come to define the experience of Auckland and I think that's really exciting." Johnston says tackling the design side of project of this size is helped by having a progressive client in publicly listed Precinct Properties.
"It is very easy to think about a commercial development as 36,000m2 of floor space and how do we build it?
"But that absolutely was not the process we went through with Precinct Properties." Instead, a workshop with Precinct's board fleshed out 10 guiding principles for the project.
"Those have been tremendously important because they're not all about commercial returns.
"That's part of it, but a lot of it is about what this project must do for Auckland and what it must do for the wider community.
"It should be symbolic of Auckland; it should represent Auckland," says Johnston.
"I think we've all agreed for a long period of time that if this project could be anywhere, if it could be in Hong Kong or Sydney or San Francisco, then that would have been a failure."
In the wider context, a number of forces are driving Auckland to become a globally relevant city, he says.
"I think five years ago, to talk about Auckland in a global context would be faintly ridiculous.
"In five years' time that won't be the case."
Johnston says population growth that projects a city of 2 million by 2033 - the equivalent of building a new Christchurch in Auckland every 10 years - is creating massive change and opportunity in Auckland.
The debate on housing that arises out of this growth isn't unique to Auckland, but increasing density, albeit with a New Zealand twist, is an inevitability, he says.
"If I'm honest I think the public debate is simplistic to the point of not being helpful.
"It's very binary; it's the quarter-acre dream vs the high-rise nightmare and those two polar extremes, neither of them are the answer.
"I appreciate it's difficult to have a nuanced discussion in a public forum but it's really important that we do and we start thinking creatively about what increased density means because it does not need to mean high-rise towers."
Alongside population growth, Auckland's emerging confidence in its unique identity will grow as it continues to diverge from the rest of New Zealand in terms of ethnicity and makeup, Johnston says.
"[Auckland] will be a young, increasingly Pacific and Asian city and again there is immense opportunity in that.
"I think we are starting to capture that in the way we think about our public spaces, in particular our streets, our parks.
"Wynyard [Quarter] is a good example of that, about starting to tell our other stories, tell stories of our culture and our past and heritage and things that actually differentiate ourselves from the world." It's coupled with a maturity about how we build infrastructure, which is moving past the post-colonial attitude of basic function at minimal cost towards a model of infrastructure saying something about us, where we live and who we are, he says.
Add in a swing in global focus to countries within a single plane trip of New Zealand with a resulting shift in our psychology of "being at the edge", says Johnston.
"The combination of those internal and external forces suggest that there is dramatic opportunity for Auckland."
Blair Johnston
• Dunedin-raised, but calls himself an Aucklander - except when it comes to rugby
• Joined Warren & Mahoney in 2006 after time in Sydney and Rotterdam
• Lead architect on the Wynyard Quarter innovation precinct
• Counts the MIT Manukau & Transport Interchange as his favourite project to date
