The seven-hundred and seventy-seventh volume of the Archives of Maryland is A Guide to Research and Writing about the History of Baltimore City, baltimorecityhistory.net (external link).

The purpose of this site is to assist researchers in the study of Baltimore History. Its emphasis is on the public record, although reference will be made to secondary sources and private records in public and private repositories. It is a work in progress and is meant to be instructive as the time and resources of the contributors permit. The initial principal contributor and editor is Dr. Edward C. Papenfuse, Maryland State Archivist, but suggestions and contributions are welcome. The hope is to make this web site a permanent, authoritative guide to research and writing about Baltimore City with its focus on the care, preservation, and access to, the public record.

Secondary sources concerning the history of Baltimore City available on the Archives of Maryland Online include the following:
Volume 705 - J. Thomas Scharf, History of Baltimore City and County including Biographical Sketches of Representative Men (1881)
Volume 706 - Genealogy and Biography of Leading Families of the City of Baltimore and Baltimore County, Maryland (1897)