O'Neill, Francis P.

Abstract The Passano-O'Neill File is an index card collection of historic structures in Maryland. It includes approximately 35,000 entries for houses, buildings, and other structures, represented across nearly 66,000 cards. The file is arranged geographically by county and then alphabetically by street address, building/estate name, or related person/family name. Many properties have multiple entries, and many entries comprise multiple cards. The file was digitized in 2021 and the digitized cards are...