SAN JOSE — Six key office projects in downtown San Jose would accomplish far more than sweeping changes in Silicon Valley’s skyline: The modern developments are poised to usher in nearly 70,000 new jobs in the urban core of the Bay Area’s largest city.

Downtown West, CityView Plaza’s redevelopment, Platform 16, 200 Park Avenue, Museum Place, and the Adobe North Tower are either under construction or are making steady development progress, and together they would dramatically change the economic base of downtown San Jose.

When all six of these projects are complete, they would together create enough office space for a jaw-dropping 68,000 employees — primarily tech workers — in downtown San Jose.

At present, downtown San Jose has roughly 43,000 workers, estimated Kelly Kline, chief economic development officer with Mayor Sam Liccardo’s office. That number doesn’t include the 4,300 office workers at San Jose State University.

Google reckons that it would employ around 20,000 to 25,000 of its tech workers in downtown San Jose once the company completes a transit-oriented community of office buildings, homes, hotels, restaurants, shops, cultural hubs, and entertainment amenities near the Diridon train station.

The transformation of CityView Plaza into a modern tech campus of three office towers would create 20,000 jobs once the mammoth project is complete, according to a new environmental impact report that is now circulating at San Jose City Hall.

The huge CityView Plaza redevelopment, which savvy Bay Area developer Jay Paul Co. is leading, would total 3.79 million square feet, including 3.57 million square feet of offices, 65,000 square feet of ground-floor retail, and lobby areas totaling 24,000 square feet.

“When complete, upwards of 20,000 employees would occupy the site,” according to the San Jose planning staff environmental report. The CityView project site is bounded by South Almaden Boulevard, West San Fernando Street, South Market Street, and Park Avenue.

With a trio of 19-story towers, connected by bridges as the centerpiece of the project, it’s expected that the 20,000 office jobs that would be accommodated at CityView Plaza could materialize in a variety of ways, according to the city environmental impact study.

“Based on leasing activity, this could vary between a single large tenant or multiple tenant configurations, each with their own goals and workspace needs,” the city report stated. Nine existing office buildings would be bulldozed to clear the way for the new office campus.

At 200 Park Ave., across the street from CityView, Jay Paul Co. is busy with the construction of a 19-story office tower totaling 875,000 square feet that could be home to 5,800 tech workers.

Newmark Knight Frank, a commercial real estate firm, has begun to scout for office tenants for 200 Park and the new CityView site.

Museum Place is just down the street from both Jay Paul projects and is being developed by the newly formed alliance of Gary Dillabough’s Urban Community and mega-developer Westbank.

Under the Dillabough and Westbank plan, the aging Parkside Hall at 180 Park Ave. Museum Place would be demolished and replaced by a dramatic new office tower totaling 850,000 square feet. Potentially 5,600 people could work in this office building.

Adobe’s North Tower is under construction and ready to blossom at 333 W. San Fernando St., around the corner from all of these projects.

The new Adobe highrise would dramatically expand the tech titan’s existing three-building headquarters campus in downtown San Jose and be large enough for 4,000 employees.

Platform 16, a three-building campus featuring 16 eye-catching terraces, broke ground in early March and will add 1.1 million square feet of offices to a now largely dormant section of downtown San Jose. Boston Properties and the Canada Pension Plan Investment Board are the co-owners of the Platform 16 project, which will sprout on a huge site once dotted by a ramshackle collection of old offices, industrial yards, and vacant lots.

“We think Platform 16, given who we are marketing the site to, can accommodate anywhere from 6,000 to 7,000 employees, once it’s fully built out,” said Aaron Fenton, vice president of development with Boston Properties. “Those thousands of jobs will clearly help the downtown, considering there are zero jobs at that location now.”

Situated near the Google transit village and perched on the banks of the Guadalupe River, Platform 16 is expected to cost $1 billion to develop. CBRE, a commercial real estate firm, is seeking tenants for Platform 16.

“Platform 16 will help activate the area, along with what Google is doing,” Fenton said. “You will see more people coming into downtown San Jose during the workweek, which will drive restaurants, retail, cultural events, entertainment events at SAP Center.”

Plus, projects like Platform 16 and Google’s Downtown West development are part of the downtown and help expand the boundaries of what is considered downtown San Jose.

“This is the first project to get a shovel in the ground in this part of the downtown,” San Jose Mayor Sam Liccardo said during the groundbreaking ceremony for Platform 16. “It will be the first of many.”