Hansen's Annex is a historic house on Main Street in Center Sandwich, New Hampshire. It is a two-story wood frame house, three bays wide and a single room deep, with a side-gable roof. The front facade has a centered entry, with flanking sidelight windows and a flat entablature. It was probably built c. 1839 by Ezra Gould, and was by 1868 owned by George Hansen, who used the house and attached barn (no longer extant) as a tavern and livery stable. Hansen's son Frank bought a house across the street, which he converted for use as a tenement, making this small house a functional annex to that property. The house is distinctive as an uncommon local example of Greek Revival styling, since most of the village's Greek Revival buildings have been lost to demolition or fire.