James Crawford Neilson, or J. Crawford Neilson, was a Baltimore, Maryland-based architect. He was born in Baltimore, Maryland in 1816. After the death of his father in 1822 the family moved to England and in 1824 to Brussels. In 1833, he returned to Baltimore and in 1835, became a member of the survey party working on the Baltimore and Port Deposit Railroad,. His supervisor was Benjamin Henry Latrobe, II, (1806-1878), later supervising engineer on the Baltimore and Ohio Railroad,, son of an equally famous architect, Benjamin Henry Latrobe, (1764-1820). It was at this time that he first became acquainted with John Rudolph Niernsee, (1814-1885), while helping to survey in the area of Martinsburg, Virginia, for the Baltimore and Ohio Railroad.