In early 20th century Washington, this area became a prestigious address through the long efforts of Mary Foote Henderson, the wealthy wife of Senator John B. Henderson, who lived nearby at 16th and Florida Avenue and spent decades promoting 16th Street in the nation’s capital. In the 1880s, she was instrumental in extending 16th Street into the undeveloped land north of here, and developers followed with grand apartment buildings. In 1900, the Balfour Apartment building rose across the street to the west at a cost of $100,000; designed by Washington architect George S. Cooper, it contained 36 large luxury apartments and was among the city’s most expensive buildings of its kind. Prestigious apartments continued to appear in the neighborhood for congressmen, military personnel, and other federal officials. The Northumberland, on the east side of the street at 2039 New Hampshire Avenue, was designed in 1909 by architect Albert H. Beers for builder Harry Wardman in a Renaissance-inspired style, with features including a public dining room, trash chutes from each kitchen, wall safes, and a telephone switchboard operating 24 hours a day since the building opened in 1910. The Beaux-Arts building on the corner was built in 1914 for the Congressional Club, founded in 1908 as a non-partisan gathering place for the spouses of members of Congress, and Mary Henderson provided the land, substantial construction funds, and her favored architect, George Oakley Totten, Jr. Totten also designed nine other mansions for her along 16th Street, which she rented to foreign embassies, though her effort to persuade the president of the United States to leave the White House for her neighborhood failed.