The earliest-known photograph of the Smithsonian Castle is currently on view in the building’s Great Hall. The photograph was taken in 1850 during the Castle’s construction and shows the two completed wings of the building: The east wing housed the lecture hall, laboratories and home for the Secretary of the Smithsonian; the west wing contained the library and the reading room. The central portion of the building, now called the Great Hall, was still empty and would remain so until 1855. At the time of this photograph, only two of the Castle’s nine towers were completed. The crane in the image rises over the North Tower, which would eventually soar 140 feet above the National Mall. The carriage porch at the front of the building would not be completed until late 1851. Architect James Renwick designed the building in a medieval revival style, which was meant to identify the Smithsonian as an educational institution.
Brothers William and Frederick Langenheim of Philadelphia took the photograph using a new process they developed in 1849 and called hyalotype (from the Greek hyalos, meaning glass, and typos, meaning image or impression). This process produced a glass negative instead of the paper negative of the talbotype process. The glass negative could then be used to print either paper photographs or glass lantern slides. Hyalotypes were highly detailed and accurate, while talbotypes usually resulted in soft, slightly fuzzy images due to the coarse paper they were printed on. The exposure time for hyalotypes was about one minute, which made the process well suited for architectural studies but impractical for portraiture. The image of the Castle was part of a set of 126 views published by the brothers in 1850. The exhibition is on view indefinitely.