The Old Naval Hospital is located on the block bordered by Pennsylvania Avenue, 8th Street, 9th Street, and E Street, SE. The images here are of the building on the Pennsylvania Avenue side, with the older photograph dating to the first quarter of the 20th century.
The bill providing for the building was approved by Congress on March 2, 1865. Construction was finished in July of 1866, and the first patients were admitted on October 1 — one Sailor and six Marines.
The Hospital, being antiquated and insufficient to modern hospital requirements, became a Hospital Corp training school between 1907 and 1911.
After that time, various uses were put to the building, though the building was empty for long spans during this period until the Navy declared it surplus in 1960.
There is a generally good history of the property here for those wanting more detail.