[Both photos courtesy of Flickr user NCinDC; old photo via Office of Architectural History and Historic Preservation, Smithsonian Institution]
Now, this space on Thomas Circle is occupied by a Residence Inn, but in the late 1800s and early 1900s it was D.C.'s first apartment building, Portland Flats. Architect Adolf Cluss was commissioned in 1880 to design the structure. It was six stories high and had thirty-nine apartments. What's cool about this photo from around 1900 is that the Washington Monument is visible in the background and the statue of George Henry Thomas can be seen in the foreground. The Portland Flats were leveled in 1962 but Cluss still has some surviving buildings in D.C., including Eastern Market.