The West Roundhouse at the Baltimore and Ohio Railroad Martinsburg Shops is the sole surviving cast-iron frame roundhouse in the world and is an important example of mid-19th century industrial building design, according to the American Society of Civil Engineers. "The roundhouse is an amazing survivor of an important era in American engineering and architectural history. Eric DeLony, chief of the National Park Service's Historic American Engineering Record, has called it 'the most important surviving cast-iron framed building in North America.'" ​​​​​​​​​​​​​​​​​​​​​Designated as a National Historic Landmark and Civil Engineering Landmark by the ASCE, the Baltimore and Ohio Railroad Roundhouse and Shop Complex contains some of the most significant surviving mid-nineteenth century structures in the United States. The complex is an authentic and complete artifact of the American Industrial Revolution. The site and structures - by virtue of their authenticity, scale, completeness, and design - offer a firsthand experience of historic mid-19th century architectural industrial space. The significance of these structures lies both with what they are and how they came about. Each building in the complex incorporates novel and sophisticated engineering solutions within a carefully presented architectural statement. While some of these points may seem subtle, they have quietly served their builders for over 120 years and hidden their significance beneath prosaic functions. The Roundhouse is the sole surviving cast-iron framed roundhouse and is an important example of mid-19th century industrial building design. Designed by Albert Fink, in collaboration with Benjamin H. Latrobe, it represents an early use of standardized, prefabricated iron structural elements to create an efficient and fire-resistant building. The Martinsburg Machine and the Frog Shops, while conventional in their construction, are typical of the level of sophistication of many industrial buildings at that time. Both structures used heavy trusses to help support the second floors. This helped to keep the first floor free of obstruction from columns yielding a comparatively large enclosed area. For mid-century rural America, the ability to a have large enclosed space unencumbered with load-bearing columns was an awe-inspiring sight. After the Civil War ended in 1865, the B&O began reconstruction of the roundhouse and the associated shops that stand on the site today. They were completed in a span of six years, from 1866 to 1872. The facilities were used until the mid 1980's when all local operations were transferred to other locations and the complex remained vacant ever since. The facility played a significant role in the railroad and the City of Martinsburg. It was a major regional transportation node and one of the major employers of the region. The history of the facility and the history of the city of Martinsburg and Berkeley County were intertwined in a number of ways. The railroads prosperity brought wealth to the region. Conversely, the decline of the railroad had a profound effect on the local economy in a cyclical manner. The loss of jobs resulted in further economical hardships. The buildings are rare and outstanding examples of their types, designed by the engineers of the B&O. It is believed that all original design concepts were developed in-house by B&O and it also appears that there was a significant influence in the design from the visionary work of Willer-le-Duc, the pioneer French architect and theorist, as well as the work of Henri LaBrouste, who was responsible for the design of the Biblioteque National in Paris, construction between 1854 and 1872, the same periods as the B&O structures. The B&O architects and engineers developed simple modular designs for cast iron components that could easily be executed in remote locations with readily available materials and components, such as bricks, wood trusses, and typical metal roofs. The designs were simple, precise, elegant and typical of the great structures of the industrial revolution which form followed function in clear ways. The architecture of those structures provided strong, visual clues as to how they were to be used. In their simplicity, they were, indeed, brilliant designs. The Martinsburg Roundhouse is the only iron framed roundhouse still standing in the world today.