Boston Properties has spent $667.4 million to retire the mortgage on 200 Clarendon in Boston, the 62-story Back Bay landmark previously known as the Hancock Tower.

The loan had an outstanding principal balance of $640.5 million at a 5.68 percent fixed rate and was scheduled to mature in January 2017, according to a press release. Boston Properties paid $667.4 million to buy U.S. government securities that will generate cash flow to pay off the loan in October 2016, the company said. The mortgage and liens on the property have been extinguished, Boston Properties said.

The transaction will trigger a loss of $23.5 million from early extinguishment of debt which will be recorded on the REIT’s fourth quarter financial statement.

Boston Properties’ strategy is to pay off or refinance debt that matures in the next two years at above-market rates, CFO Mike LaBelle said in a statement.

Boston Properties acquired the iconic structure, which is New England’s tallest building, in 2010 for $930 million from Normandy Real Estate Partners and Five Mile Capital Partners, which had picked it up in 2009 for $660.6 million in foreclosure.