The Overseer's House was a significant building in the history of the Welham Plantation. It was constructed around 1835 and continuously occupied until the mid-1960s. The walls of the original construction were made of bousillage, a mixture of mud and moss. Later on, it was changed to plaster over wooden laths. When the building was relocated to the Rural Life Museum, the front wall was altered to briquette-entre-poteaux, which refers to brick between posts. The house was donated to the museum by L. Keller and Company. The son of Robert Keller, Jr. also visited the place where he was born. However, the Welham Plantation was eventually sold as an industrial site to Marathon Oil in 1975, and the "Big House" was demolished in May 1979.