This townhouse renovation/addition is in the smallest landmarked district in the city, the Fillmore Place Historic District in Williamsburg. In front, we restored the historic stoop, façade and cornice. Inside, we reorganized the home into a four-story single-family house with a separate streetside studio apartment on the basement level. In the rear yard, we built a three-story, floor-to-ceiling, north-facing glass addition which provides a double-height living space with fireplace on the basement and parlor floors, two bedrooms on the second floor and a new terrace on the third floor. Electric heat pumps heat and cool the space and a buried detention tank in the rear yard guards against storm water surges.