On March 4th, 1857, James Buchanan was sworn in as the 15th President of the United States. To celebrate the occasion, John Wood took the first known photo of a Presidential inauguration. The long exposure time captures the movement of the crowd of upwards of 25,000 people who came to witness the inaugural address. In the process of making history, Wood preserved in interesting moment in the building's history.
In 1857, the Capitol Building was in the midst of a prolonged, expensive construction period. Marble blocks littered the east plaza, causing the supervisory engineer to construct a wooden platform over the stones to provide a safe viewing area for the inaugural crowd. The wooden planks are plainly visible in the forefront of the image.
On the right of the photo people can clearly be seen standing outside the windows of the second floor of the still unfinished Senate wing expansion. The top of the Capitol is out of frame, most likely on purpose to disguise the lack of dome, which would not be fully complete for another four years. Of course, the scaffolding is still visible along with brave souls catching a birds eye view of Buchanan.
For comparison, below is a photo of the Capitol Building taken during construction sometime between 1857 and 1863.