Seniors raising their grandchildren in D.C. who cannot afford market-rate housing now have a new option available to them.

Mayor Muriel Bowser joined the development team Thursday to celebrate the opening of Plaza West, a 223-unit Mount Vernon Triangle affordable housing project with 50 units reserved for "grandfamilies."

The 50 "grandfamily" units are designed for grandparents raising young children and are set aside for those making 30% to 40% of area median income. It is the first project with these types of units in D.C., which says it is the ninth city in the U.S. to implement a "grandfamily" residential program.

The 12-story development at 1035 Fourth St. NW and 307 K St. NW also includes 173 units reserved for individuals and families making 50% to 60% AMI and 11 units for Department of Behavioral Health clients. The development also features a "grandfamilies village" with community resource offerings and 9,500 SF of outdoor recreational space. Its amenities also include a library, children's activity space, a fitness room and a community room.

The project is within a half-mile of the Mount Vernon Square, Gallery Place and Judiciary Square Metro stations. It is also two blocks from a Safeway grocery store, and the neighborhood has several other restaurants and service retailers nearby. The project is a partnership of several D.C. agencies and Golden Rule Plaza Inc., a D.C.-based affordable housing nonprofit and affiliate of the Bible Way Church.

“As our city continues to grow and age, we’re committed to making investments in innovative programs — in housing, education, childcare, and more — that will set more families up for success,” Bowser said in a release. “Plaza West is an example of how we are ensuring residents and families of all backgrounds and income levels have access to safe and affordable places to live across all eight wards.”