Clara Barton’s post-Civil War office, where the battlefield nurse had helped families find missing soldiers, may finally get the care and respect it deserves.

The top floor of an old brick commercial building in downtown Washington was Barton’s apartment and office where she collected donated medical supplies for the battlefield and later ran the Missing Soldiers Office. She closed the office in 1867, storing files and personal clothing in the crude attic above her rooms. She never came back for them, and they stayed in their hidden storage space until 1996, when a federal government carpenter discovered the cache while preparing the building for demolition.

The discovery saved the building but little else had happened until today when officials of the National Museum of Civil War Medicine of Frederick, Md. announced they had signed an agreement with the building’s owner, the General Services Administration, to open the Clara Barton Missing Soldiers Office Museum in that third floor space....