Google will move its UK headquarters to King's Cross following a $1bn (£628m) property deal.
The 2.4-acre brownfield site between King's Cross and St Pancras stations in central London will be home to a seven-floor building and an 11-floor building, which are set to be complete by 2016.
All Google's London staff, currently based at separate offices in Victoria and Holborn, are expected to relocate to the new premises following its completion. The site will also be used for houses, shops and other offices.
"This is a big investment by Google, we're committing further to the UK – where computing and the web were invented," said Matt Britin, Google's vice-president for northern and central Europe.
"It's good news for Google, for London and for the UK," he added.
Meanwhile, Japanese firm Sony has announced it will sell its US headquarters in New York to retail estate investor The Chetrit Group for $1.1bn (£690m), and then lease it back for at least three years.
The move comes after four years of losses as a result of weaker demand for its products.
"Given the opportunities and challenges in the current economic and real estate landscape, selling 550 Madison now is a timely and logical strategic move," said Nicole Seligman, president of Sony Corp. of America.
The Japanese firm said it had forgotten "the power of wow" in a presentation at CES earlier this month. It's widely speculated that Sony will reveal its next-gen games console, the PlayStation 4, at some point this year.