WASHINGTON — Akin Gump, one of D.C.’s biggest lobbying firms, will leave its longtime New Hampshire Avenue headquarters in Northwest for new construction at 20th and K streets.

Akin Gump will be downsizing a bit, taking the top four floors in one of two buildings that are being repositioned as the Alexander Court development at 2001 K Street with 185,000 square feet. Its current headquarters, at 1333 New Hampshire Avenue, is 212,000 square feet.

The company’s new space will be called the Robert S. Strauss Tower, named after Akin Gump’s founder. The same name currently adorns its New Hampshire Avenue building.

Akin Gump will make the move to the new space in 2019. The Alexander Court project is currently under construction.

“Akin Gump’s Washington office opened nearly half a century ago and grew to become not only the firm’s largest office but also a Washington institution,” stated Akin Gump chairperson Kim Koopersmith. “This move ensures that we will remain a fixture in our nation’s capital for many years to come.”

The company’s D.C. offices, which opened in 1971, house more than 230 lawyers and nearly 500 total personnel.

Alexander Court, a joint venture by Rockrose Development and Spitzer Enterprises, will include on-site child care, a coffee and wine bar, rooftop terrace and fitness center.