JOHN YANG: Some see older buildings as revered artifacts that have stood the test of time.

Others see them as occupying sites that could be used for new development.

Ali Rogin went to one place where that tension is playing out Phoenix which is a rich source of one specific style of architecture.

ALI ROGIN (voice-over): In the Valley of the Sun, nature's gifts abound, so to do manmade treasures that help tell the story of postwar America.

Phoenix is a trove of mid-century modern architecture style that mirrored the optimism of America after soldiers returned home from World War II.

Designs focused on function, creative use of materials and a connection to nature.

ALISON KING, Modern Phoenix: It's what we call desert architecture.

ALI ROGIN: Alison King is a professor of design history and runs Modern Phoenix, an archive and community for enthusiasts of mid century modernism.

ALI ROGIN: Why is Phoenix such a hub for mid-century modern architecture?

ALISON KING: Well, this really was the land of opportunity in the post war era.

ALI ROGIN (voice-over): In the 40s, more than a million young men trained for deployment at military bases throughout Arizona.

After the war, many of those GIs returned, drawn by cheap land and a warm climate.

And it was two of those out of town servicemen, Al Beadle and Ralph Haver, who became the architectural founding fathers of Phoenix, ALISON KING: they saw a lot of opportunity for growth, as well as for business.

And so many of these architects were part of the pattern of growth of our city to help build the civic buildings, the schools, the banks, the infrastructure, and of course, most importantly, the housing to house these people.

ALI ROGIN (voice-over): When Beadle executive towers condo building opened in 1963, it was the tallest in Arizona, billed as vertical living for the upwardly mobile.

ROBRT PELA, Writer: It's the Frigidaire flair.

ALI ROGIN (voice-over): Writer Robrt Pela tried not to change a thing in his unit, including the appliances.

ROBRT PELA: When you buy an old building, I think you're beholden to honor it.

Because if we continue to rip down our visual heritage, our architectural history, we will never have any character.

ALI ROGIN: In Phoenix and around the country, you'll find Mid Century Modern enthusiast who are passionate about protecting these buildings.

But there's another school of thought that believes sometimes preservation impedes progress.

ADAM MILLSAP, Stand Together Trust: It can restrict the growth of that area, increase the price of housing and make it difficult for neighborhoods and communities to adapt as the situation around them changes.

ALI ROGIN (voice-over): So economist Adam Millsap is a senior fellow at Stan Together Trust, a philanthropic organization funded by billionaire Charles Koch, he says he's not opposed to all historic preservation.

ADAM MILLSAP: I think it's more about how it can be misused.

But I think that's where you run into problems and you just start preserving things for a variety of reasons that don't necessarily have to do with preserving history but might be done for other purposes.

ALISON KING: We're in Marlin Grove, which was designed by Ralph Haver in the mid-1950s.

ALI ROGIN (voice-over) Alison King says not every piece of modern architecture can or should be saved.

But she and other preservationists believe Arizona's laws make it harder to protect historic buildings.

That includes a 2006 measure that strengthened the rights of property owners when faced with government attempts to take private property for public use what's known as eminent domain.

ALISON KING: It's not always easy to convince property owners that what they have is worth putting on some sort of register to afford it protection.

ALI ROGIN (voice-over): King and her peers have had some high profile victories.

In 2012 they blocked a developer from tearing down a home built by renowned architect Frank Lloyd Wright for his son demonstrating in front of the house and convincing the city to delay demolition.

MAN: Right now at six trying to preserve Arizona history this mid-century modern home could be demolished.

ALI ROGIN (voice-over): King's latest challenge saving white gates and iconic Beadle home never designated as historic.

Its new owner intends to build an entirely new house but there's hon demolition until mid-April.

King and her community are trying to convince the owner to sell.

ALISON KING: These buildings act as living textbooks to help us understand the progression of time and because they endure for so long, I see very little reason why they shouldn't endure much longer for future generations.

ALI ROGIN (voice-over): That's what architect Tyler Sternberg and his wife Vanessa had in mind for their Ralph Haver design home.

Haver's trademark was mass produced but customizable dwellings perfect for the post war baby boom.

TYLER STERNBERG, Architect and homeowner: We kind of had a couple kids right when we bought this house and we knew we needed to grow a little bit more.

ALI ROGIN (voice-over): In the 1950's Haver hoods were marketed as middle class mechas.

ALISON KING: What's so cool about Haver homes is you can tinker with them.

Maybe they were they were designed that way because they were so modest in the beginning, the idea was to let families grow into them.

ALI ROGIN (voice-over): But not all families are welcome.

Some homes were advertised as highly restricted code for whites only.

The deeds to many historic Phoenix homes still have those restrictions, which some homeowners have tried to expunge.

But experts like Rashad Shabazz believe that history should remain exposed.

RASHAD SHABAZZ, Arizona State University: Retaining these restrictive covenants in the deeds are a reminder of Arizona's relatively recent history around racism that is really imbued into the housing market.

ALI ROGIN (voice-over): Shabazz is a Professor of Geography and African American Studies at Arizona State University, the deed to his home has a restrictive covenant.

RASHAD SHABAZZ: 50 or so years ago, I couldn't have moved here with my family, and other black and brown people couldn't have moved into this neighborhood.

It really helps us to see how deeply institutionalize it is.

But it's also a reminder of how close we are to it.

ALISON KING: I think that it's important that we as citizens feel tied to the roots of our city and understand the story of how our city developed.

And as well, many of these works of architecture are actually works of art.

CRAIG DEMARCO, Upward Projects: He was glamorous to walk down the stairs.

ALI ROGIN (voice-over): There's no mistaking the artistry inside the office of Upward Projects, a restaurant group located in the Phoenix financial center, designed in the mid-60s for a booming banking industry.

CRAIG DEMARCO: When we were looking for office space really wanted something architecturally relevant to go with our adaptive reuse style of the way we do business.

ALI ROGIN (voice-over): Like Phoenix's mythical namesake, the process of adaptive reuse creates new structures from the remains of the old and 2001 co-founders, Craig and Chris DiMarco started that process inside an old post office.

CRAIG DEMARCO: We fell in love with the architecture, the age of the building, the neighborhood that surrounded it and giving it a second life.

ALI ROGIN (voice-over): The post office reopened as Postino, a wine bar that since grown to 25 locations across six states at 40 years old Postino's original site was hardly historic.

CRAIG DEMARCO: I think as time has gone on, people have realized they are special they need to be preserved.

They need to be celebrated and recognized.

ALI ROGIN (voice-over): And like the wines on the menu with Postino, preservationist say these buildings will only get better with time.

ALISON KING: Architecture is shelter, essentially.

And the way that we shelter each other and take care of each other is a symbol of the story of who we are as humans.

ALI ROGIN (voice-over): For PBS News Weekend, I'm Ali Rogin in Phoenix.