The Horace Sheldon House is a T-shaped, one-and-a-half storey house constructed in 1865 by Horace Sheldon with sandstone quarried from his 80-acre property. A variation of the Ontario Regency cottage style, the house features a symmetrical façade, projecting eaves and verges, a corbelled cornice, a moulded frieze, a three-sided verandah with decorative trellis work and open railing, casement windows flanked by wooden shutters, and a front door with side-lights and stone voussoirs above. The rear addition was completed in the 1880s under the supervision of his son, Richard Sheldon.

Horace Sheldon was a Loyalist who helped defend Canada during the War of 1812, and as a result, was granted the tract of land that the house sits on. Stone farmhouses were typical during Portland's early development.