100 First Plaza, Modern skyscraper in Financial District, San Francisco, US

100 First Plaza, also called the Delta Dental Tower, is a 27-story, 136 m office high-rise at 100 First Street in San Francisco's Financial District, completed in 1988. Its design uses several setbacks, a grooved and faceted façade, rooftop curtain walls and a 19 m spire. The roof height is 117 m.

Completed in 1988, 100 First Plaza was built to designs by the San Francisco firm Heller & Leake, now Heller Manus, in a postmodern style. The sources disagree on the architect: English-language references credit Skidmore, Owings & Merrill, while the French account names Heller & Leake. Its roof reaches 117 m, with a 19 m spire above the setbacks and faceted façade.

The tower's name comes from its address at 100 First Street, and its alternate name, Delta Dental Tower, reflects a tenant. Offices inside have housed firms such as Okta, AppsFlyer, Andersen Tax, HomeLight and ADR Services, so the lobby and elevator banks are part of a working corporate address rather than a public attraction.

The building offers direct access to public transit, with BART stations within walking distance for convenient commuting. Multiple elevator systems efficiently move people between floors throughout the day.

The 19 m (62 ft) spire on the roof is easy to miss from street level; the building's stepped setbacks and grooved, faceted façade make it read differently from each approach. Tenants listed in the sources include Okta, AppsFlyer, Andersen Tax, HomeLight and ADR Services.