The Martin Luther King Jr. Memorial Library (MLKML) is the central facility of the District of Columbia Public Library (DCPL). Ludwig Mies van der Rohe designed the 400,000 square foot (37,000 m²) steel, brick, and glass structure, and it is a rare example of modern architecture in Washington, D.C.ConstructionThis library was Mies's last building, his only public library, and his only building constructed in Washington, D.C. The building was completed in 1972 at a cost of $18 million. Maintenance was then somewhat neglected and there were problems with the HVAC system. DCPL has recently restored lighting on the entire first floor. DCPL has also recently completed elevator and restroom renovations throughout the building.On March 4, 2017, the building closed to begin a modernization, including a major reconstruction of the interior of the building. The modernization process is expected to last for three years, with a planned cost of $208 million and a re-opening in 2020. A outdoor terrace and green roof will be added. Interim services for the central library begin May 8, 2017. A "Library Express" location and administrative offices will be located at 1990 K Street NW and an operations center established at 1709 3rd Street NE.Landmark statusOn June 28, 2007 the District of Columbia’s Historic Preservation Review Board designated this building a historic landmark. The designation, which applies to the exterior as well as interior spaces, seeks to preserve Mies' original design while allowing the library necessary flexibility to operate as a contemporary library facility. It was listed on the National Register of Historic Places in 2007.