Do you recognize the Treasury Building? This photo shows it back in 1860, before the Civil War. Five years later the building became a crime scene, when Mary Harris shot the Treasury clerk who had jilted her and then walked free.
Source: Library of Congress
The cows are throwing me off…..
It looks like there was some construction debris. South Wing of the building was constructed finished up by 1861 but the the West Wing was being worked on between 1862 and 1864.
They are oxen used for hauling in the city, particularly building works.