The construction of the Rotunda in 1921, designed by architects Simonson & Pietsch in the neo-Georgian style, marked a radical change in the design of business campuses in the twentieth century. Traditionally, businesses in the banking industry were located in dense downtown financial districts. The Maryland Casualty Company changed this notion after outgrowing its Tower Building at 222 E. Baltimore Street and moving to the more residential Hampden neighborhood. It set the example for future suburban business campuses and helped rein in an era of pastoral capitalism.
The Maryland Casualty Company purchased the Dulin Estate in 1919 and established on the twenty-five acres an extensive business campus that included a number of impressive amenities, including a clubhouse with a dining room, an auditorium that could seat 1,500 guests, a landscaped park, tennis courts, and a baseball diamond. The idea was to provide workers with an idyllic business campus removed from the hustle and bustle of the downtown area. What is now known as the Rotunda was the company's administration building. The H-shaped building features a distinct bell tower and clock that exists today as a landmark of the Hampden community.
The Rotunda was nearly demolished in 1969 after the Maryland Casualty Company outgrew the four-story building. They considered erecting a larger office building in its place, but developer Bernard Manekin convinced the company to turn it into a retail and office space. The result was one of Baltimore's first adaptive reuse projects and grew to include a shopping mall, movie theater, office spaces, and a grocery store.
In 2005, the shopping center had already fallen into decline and New Jersey based developer Hekemian and Company bought the property. They began planning a mixed-use redevelopment project on the site that would transform the historic location into an upscale residential/commercial campus. The project stayed in the planning phase for eight years due to a national recession and community concerns. A coalition of neighborhood councils formed the Mill Valley Community Council to push back against the new development. Amongst a number of concerns, community leaders felt that the new Rotunda was not being designed to serve neighborhood residents and that new retail stores would take business away from the local establishments on Hampden’s "Avenue."
In September 2013, Hekemian and Co. broke ground on the site. The construction will bring new retail and living spaces to the Rotunda, as well as parking garages. Supporters argue that the development will breathe new life into the Rotunda and revitalize the struggling shopping mall inside, and according to the project’s website, "will mark the return of a Baltimore landmark."