Hunter Partners Plans 246,563-Square-Foot Office Building at Sunnyvale's CityLine

Hunter Partners is planning a new five-story, 246,563-square-foot office building in downtown Sunnyvale, California, and is seeking approval from the City of Sunnyvale to build it. The project would rise at the CityLine development near the Sunnyvale Caltrain station, in a market where developers have been hesitant to pursue new projects as the office sector resets.

Hunter Partners' CityLine Office Proposal

The proposed building would be located at 300 S. Mathilda Ave. within the CityLine mixed-use development. Beyond the office space, Hunter Partners is planning about 7,000 square feet of ground-floor retail, a rooftop terrace and a conference room.

The site had previously been entitled for office development but was never built. The current proposal is a redesigned project designed by Gensler.

Silicon Valley Office Market Context

The proposal arrives as Silicon Valley office fundamentals show signs of improvement. Silicon Valley office vacancy fell to 15.9% in the third quarter of 2026, down 30 basis points from the prior quarter and 160 basis points from a year earlier.

New supply remains scarce. No office space was delivered during the quarter, and only about 60,200 square feet remained under construction, an 88.2% decline from a year earlier. Average asking rents reached $4.98 per square foot per month on a full-service gross basis, up 2.7% year over year.

A separate second-quarter survey put the average asking rent at $5.09 per square foot, with year-to-date net absorption above 1.3 million square feet, seven consecutive quarters of positive absorption and second-quarter vacancy of 15.2%. The two sets of figures reflect different survey periods or methodologies.

CityLine's Recent Leasing Activity

CityLine has drawn significant technology leasing. Databricks leased 455,000 square feet across two office buildings at 200 W. Washington Ave. and 250 W. Washington Ave. Those buildings are fully leased, with additional demand from CrowdStrike, helping establish downtown Sunnyvale as a technology office node.

The development combines offices, housing, retail, dining and access to Caltrain, features that distinguish it from older suburban office inventory.

Market Implications for Sunnyvale Office Development

Even with recent gains, vacancy near 16% means tenants retain negotiating leverage, and speculative construction remains difficult to finance. At nearly a quarter-million square feet, the Hunter Partners project may require substantial preleasing or an anchor tenant before construction financing becomes available.

The proposal points to selective interest in new Silicon Valley office development, focused on transit-oriented, amenity-rich space after a prolonged period of limited construction.

Sources

• Kidder Mathews: AI Surge has Hunter Partners Planning New Office Project at Cityline in Sunnyvale