The Post reports that Publisher Katharine Weymouth made the announcement in an email to staff Friday morning. She says the company's goal is to find "a more modern, bright, open and efficient building."
Weymouth says The Post isn't tied to the location at 15th and L streets, Northwest, because its printing presses have not been located there for more than a decade.
The District of Columbia government assesses The Post's properties at nearly $80 million. Weymouth's memo says the company has not yet decided on where or when it might move.
The Herald is owned by the Washington Post Co.
Some other major metropolitan newspapers have moved out of or leased their buildings, driven by industry struggles and the value of urban real estate.