It would have been easy for Fran Dieudonne and Sharon Au to knock down the homes they bought in Manoa and rebuild. One potential buyer for Dieudonne’s property told her he was planning to do just that, and Au’s was in shambles.

But a sense of history and place seems to be a theme in the women’s lives. Au is a real estate agent who has been involved in the restoration of 11 vintage homes in Honolulu, with her own home an elegant gem of design. Dieudonne is a journalist and nurse who has worked on many Pacific islands, but it was almost by accident that she wound up owning and preserving a remarkable piece of Hawaii’s architectural past.

Located doors apart on Sonoma Street in lower Manoa, the two homes are among seven listed on the state Register of Historic Places that will be open to the public Sunday for the Historic Manoa Walking Tour. The biennial event sponsored by Malama Manoa is aimed at promoting the importance of historic preservation.

Dieudonne’s home, at first glance, is a modest California ranch-style bungalow perched high above street level. One has to climb several stairwells to get to it, and the immediate urge is to turn around to look at the spectacular view, which spans Kaimuki, Diamond Head, Waikiki and Ala Moana.

But little features suggest an attention to detail someone who specializes in design might appreciate, such as the amoeba-like shapes traced into the patio floor as a kind of nonskid surface, or the subtle aspects of the wrought-iron stair railing.

The home was the personal residence of Theodore Vierra, a pioneer among local architects. He designed and built the home for himself and his two sons in the mid-1940s, when he was director of architecture for the Hawaiian Sugar Planters’ Association.

Dieudonne, who has written a book about Vierra, said he had a childhood fascination for architecture and design.

"When he was at Kamehameha Schools, they would let him sit and draw for six hours a day," she said.

Vierra was awarded a competitive scholarship to study architecture at Harvard and worked at several mainland firms before returning to the islands. He was the first Native Hawaiian admitted to the American Institute of Architects. Among his many projects are the famous open-air terminal at Honolulu Airport, the Radford High School campus, several buildings at the University of Hawaii and Kamehameha’s Kapalama campus, as well as numerous businesses and residences.

But Vierra was also known for his modest, unassuming projects, designing affordable homes for plantation workers and returning war veterans.

His home follows that mold. The walls are painted cinder block, precisely placed so the grout lines create a geometric design. The dining-room floor is a very practical brown cement.

The living room shows some of Vierra’s trademark design features, especially the open-beamed ceiling that guides visitors toward the large picture window, which looks directly at Diamond Head. Dieudonne even managed to rescue some of Vierra’s furniture before it was sold off or dumped.

Dieudonne had lived next to the home for years before buying it six years ago. She then held an open house. Visitors saw the place and urged her to renovate.

"We didn’t have the money," Dieudonne said. "A year later, the historic people came up. They came and said, ‘Oh, original hardware! Original cabinets! Don’t touch it!’ And so here it is."

Au’s home also has the original hardware and cabinetry, but they would be easy to overlook in her Craftsman-style home designed and built by J. Alvin Shadinger in 1929. With high ceilings, arched doorways, a fireplace and beautiful hardwood floors, the home has a mansion-like feel while being cozy at the same time. All of that, however, came as a bonus for Au.

"I fell in love with the veranda," she said. "When I came to see the property, it wasn’t on the market and it was all shut up. I couldn’t even see in the windows — it had curtains — but I put in an offer just based on the veranda because I always wanted outdoor living."

She spent almost $500,000 restoring it, including new utility lines and repouring concrete footings in the foundation to keep it stable on a black-sand slope. Leaks in the roof had caved in portions of the ceiling and layers of wallpaper covered the walls.

Although she reconfigured the kitchen, Au went to extra lengths to save what she could, including a stainless-steel tub, porcelain sink, the crystal drawer and cabinet pulls, and the Shaker-style cabinetry, with her carpenters taking down each panel to refinish. She had a master carpenter replace the sash windows, which use ropes and weights to ease the windows open and closed and slide into pockets above the window frame for full ventilation.

For things like damaged moldings, carpenters had to make a new drill bit to rout out a new piece. At one point, Au had 14 vendors working at the same time on various projects throughout the house. Most of the work, save for the concrete work on the foundation, was done in one month, with Au on site constantly.

"Reclaim, restore, reuse, refurbish," she said. "It’s really going green, being sustainable, when you restore a property rather than tear it down and bring it to the landfill. That is a huge burden on the landfill.

"I’m lucky enough to be a caretaker of (the home). … Being part of this walking tour is the opportunity to share the architecture with others."