SAN JOSE — An office complex proposed by a global and local development alliance would preserve a prominent office building and create a new office and retail tower poised to be a new gateway to downtown San Jose.

The new office and retail tower would sprout at 255 W. Julian St. and connect via a sky bridge to the well-known Davidson Building in downtown San Jose, according to a proposal being circulated by world-acclaimed developer Westbank and local developer Gary Dillabough.

The Davidson Building site is deemed to be a choice location for development in downtown San Jose, being perched prominently next to the interchange of State Route 87 and Julian Street, and near normally bustling San Pedro Square.

Arbor tower in downtown San Jose at 255 W. Julian St., concept. Studio Gang / Westbank

Named after famed San Jose developer, builder of affordable homes, and philanthropist Charles Davidson, the Davidson office building will be preserved while Westbank and Dillabough develop a modern and considerably taller office and retail tower on the surface parking lot behind the existing building.

Westbank and Dillabough say they are deliberately attempting to preserve and update what’s useful, while at the same time developing what is underutilized but filled with potential.

“This is the same theme with all of our projects,” said Andrew Jacobson, head of development for Westbank’s San Jose initiative. “Sustainability is very important.”

Canada-based Westbank and Dillabough, who heads a San Jose-based real estate firm called Urban Community, still plan dramatic changes at the site on West Julian Street.

Downtown San Jose’s Arbor tower and a connecting sky bridge to the Davidson Building (left) at 255 W. Julian St., concept. Studio Gang / Westbank

Arbor, in keeping with Westbank’s over-arching theme of green and sustainable development, is the name of the office and retail tower that Westbank aims to develop next to the Davidson building.

The new tower would total 512,000 square feet and consist of offices and ground-floor retail, including potentially one or more restaurants.

Arbor tower at 255 W. Julian St. in downtown San Jose, concept. Studio Gang / Westbank

Westbank intends to connect the old building with the new one through a sky bridge as well as an underground tunnel.

It makes sense to preserve the older building, Westbank says, because the debris would otherwise be headed to the garbage dump.

“When you think of our cities, and wanting to respond to climate change, the most effective way to achieve sustainability is to keep what is already built,” Jacobson said.

That’s the idea behind keeping the Davidson Building intact, even though the six-story building was constructed in 1984, nearly four decades ago.

“It’s better to reuse something if you can, don’t tear it down, don’t just put it in the landfill and build something new,” Jacobson said.

Westbank also recognizes the key location of the Davidson Building, according to the company’s vision book for downtown San Jose that the developer has distributed to real estate brokers.

“Adjacent to a major entryway into downtown from the north, Arbor sits among other residential developments,” Westbank stated in the vision book.

Some of the residences are new, with proposals in the pipeline for more housing. And just down the street are San Pedro Square and Little Italy.

Also nearby are parks and the Guadalupe River and its tree-lined banks.

There’s more, however. Jetliners using San Jose International Airport zoom above the building regularly. Vehicles crawl or zip nearby on Highway 87. The area can be windy. The site is well-exposed to sunlight and isn’t hemmed in by big adjacent towers.

“The project site confronts widely disparate urban and environmental conditions on all four sides,” Westbank states in its vision book. “Each side must negotiate different relationships of urban connectivity, noise and air quality, and strategies for harvesting natural light, fresh air, and energy.”

Westbank compares and contrasts its proposed renovation of the Bank of Italy historic tower in downtown San Jose with what the company plans for the Davidson site.

The Bank of Italy renovation is a project that Westbank acknowledges is a clear-cut candidate for what developers call “adaptive reuse,” with its elegant spire and distinctive Mediterranean Revival Beaux-Arts architectural style.

Workspaces in Arbor, an office tower at 255 W. Julian St. in downtown San Jose, concept. Studio Gang / Westbank

The Davidson Building, while having a namesake in a true San Jose legend, isn’t as definitive a candidate for preservation.