The new owners of Minerva House in Montague Close say that they see "significant development potential" for the prime site on Bankside close to London Bridge.
Great Portland Estates has bought the six-storey office and residential block – which stretches from St Mary Overie Dock in the west to Cathedral Square in the east – for £60 million.
The offices are leased to Winckworth Sherwood and Ipsos Mori with leases running until 2021 and 2022.
In 2005 the building changed hands for £42 million.
"We are delighted to have acquired Minerva House, the first purchase following our £140 million equity placing announced less than one month ago," said Toby Courtauld, chief executive of Great Portland Estates.
"This property meets our objectives of an accretive initial yield with an attractive prospective total return due to its low rents and multiple refurbishment possibilities.
"Longer term, this river-fronting site provides us with significant development potential."