Harford County was created in 1774 from territory in eastern Baltimore County, and Bel Air was designated the county seat in 1782. Development here centered on the courthouse and approximately forty blocks along Main Street. After the first courthouse was destroyed by a fire in 1858, officials moved quickly to replace it, hiring Baltimore architect Neilson that same year. He designed a two-and-a-half-story red brick Italianate pile with round-arched openings and topped by a cupola. After the Civil War, Bel Air and Harford County grew substantially due to the construction of the Maryland and Pennsylvania Railroad, the burgeoning canning industry, which amplified the value of local agricultural production, and other financial interests. Regionally prolific architect Dempwolf of York, Pennsylvania, was hired in 1904 to design large additions that covered the front and rear of the Neilson courthouse, creating an I-shaped plan. Dempwolf’s additions were distinct, but complementary, retaining the red brick of the earlier courthouse and shifting to a more Georgian appearance. A less complementary addition looming at the rear of the ensemble dates to 1981.
The commercial district along the sections of Office and Courtland streets flanking the courthouse include a representative assortment of small-scale offices, stores, and hotels built from the mid-nineteenth to the early twentieth century. Baltimore architect George Archer designed the Beaux-Arts classical former First National Bank Building (12 Office Street) in 1900. Unfortunately, his 1889 building for Har-ford National Bank was demolished for the 1980s courthouse addition. The Harford Mutual Building (1930; 18 Office) is a two-story office building with Colonial Revival details, including paired limestone pilasters, keystones, and cornice. Designed by John B. Hamme of York, Pennsylvania, it now serves as a county office. The building (1869) at 21 W. Courtland was constructed as newspaper offices for The Harford Democrat. It now has a Colonial Revival facade from a 1940 renovation by Alexander Shaw of Bel Air and Taylor and Fisher of Baltimore.