San Francisco's tallest skyscraper, designed by US firm Pelli Clarke Pelli Architects, has completed as part of a major development in the city's Downtown area.

Reaching 1,070 feet (326 metres) and 61 storeys tall, the Salesforce Tower celebrated its official opening on 8 January 2018 and will become the headquarters of cloud computing company Salesforce.

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Although interior fit-outs are still required before employees can move into its 1,400,000 square feet of office space, the building appears entirely finished from the outside.

The glass-wrapped skyscraper has curved corners and a form that gradually tapers towards its top, described by Pelli Clarke Pelli as "the simple, timeless form of the obelisk". Louvres criss-cross the facades to create a grid, shading the windows from direct sunlight.

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"The walls rise past the top floor to form a transparent crown that appears to dissolve into the sky," said the firm. "Carved into the tower top is a vertical facet that will be lit at night."

Salesforce Tower eclipsed the height of the Transamerica Pyramid, which at 853 feet (260 metres) held the title of the city's tallest since it completed in 1972.

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However, it misses out to Los Angeles' Wilshire Grand Center to the claim of tallest building west of the Mississippi.

Located at the corner of Mission and 1st Streets, the Salesforce Tower is directly connected to the Transbay Transit Center – a new transport hub for the wider area, now renamed the Salesforce Transit Center – and the 5.4-acre Salesforce Park on its roof.

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Also designed by Pelli Clarke Pelli, the complex will house 11 Bay Area transit systems and is scheduled to complete later this year.

"Together, the two buildings represent a novel approach to public-private collaboration and sustainability in an urban setting," the firm said.

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Pelli Clarke Pelli won the competition for the project in 2007 – marking a shift in technology companies investing in Downtown San Francisco, rather than nearby Silicon Valley and surrounding Bay Area.

Another San Francisco skyscraper has been in the news for some time. The residential Millennium Tower was discovered to be sinking and leaning a few years ago and continues to do so, although engineers came up with a potential fix in July 2017.