David M. Straub
House history -- the record of who lived in a building, who owned it, and how its address changed over time -- is a central concern of genealogical and local history research. Wikidata and OpenHistoricalMap together provide an open-data infrastructure, CC0-licensed and capable of representing this data: Wikidata through its linked-data property model with temporal qualifiers, OpenHistoricalMap through historical building footprints with start and end dates. What has been missing is a domain-specific tool that makes contributing and discovering building history accessible to genealogists and local historians. Domus fills this role: a map-based web platform that guides users through structured, crowdsourced editing of building records in Wikidata and displays corresponding OpenHistoricalMap footprints. The application requires no custom backend -- authentication, data reading, and data writing all operate through public APIs in the browser, and all data are stored under CC0 in public collaborative databases. This paper describes the genealogical data model, the architecture, and key technical design decisions.