Built in 1802, this large residence at 14 Walnut Street is among the oldest extant mansions on the South Slope of Beacon Hill and includes a large hidden garden behind a granite block retaining wall. John Callender, Clerk of the Supreme Judicial Court of the Commonwealth, purchased land at the corner of Mount Vemon and Walnut streets for $2,000 and immediately started construction on his requested “small house finished for little money $5,000-$7,000”, but this was anything but modest. The house originally had its primary facade facing Mount Vernon Street, but in 1821, Walnut Street was lowered by city officials, so Callender had the granite retaining wall built for the garden and new entry built on Walnut Street. Mr. Callender lived here until his death in 1833 and the property was purchased by members of the Lyman family and later by Harriot Curtis (1881-1974) an early amateur female skier and golfer who used her fortune as a philanthropist, funding medical facilities in Boston for impoverished immigrants and served as dean of women in Hampton Institute in Virginia, an HBCU from 1927-1931. The most significant owner, Ellery Sedgwick (1872-1960), lived here from 1908 until his death in 1960. Sedgwick worked as editor of the Atlantic Monthly (now known as The Atlantic), and under his ownership, the magazine became one of the most circulated magazines in the world. The Callender-Sedgwick House features unique flushboard siding, providing a seamless surface that resembles a masonry wall when painted earth tones and a 19th century oriel window. The brick end elevation is punctuated with bays of hung windows and the recessed entry with a long, granite garden wall which has been well-preserved by owners.