Embassy Row is the informal name for the section of Massachusetts Avenue, N.W. between Scott Circle and the North side of the United States Naval Observatory, in which embassies, diplomatic missions, and other diplomatic representations are concentrated. By extension, the name may be used to encompass nearby streets which also host diplomatic buildings.HistoryConsidered Washington's premier residential address in the late 19th and early 20th centuries, Massachusetts Avenue became known for its numerous mansions housing the city's social and political elites. The segment between Scott Circle and Sheridan Circle gained the nickname "Millionaires' Row".The Great Depression caused many to sell their homes. The expansive old estates proved well-suited for use as embassies, and also as lodges of social clubs, giving Embassy Row its present name and identity. Some of the avenue's newer buildings were purpose-designed as embassies, starting with the British Embassy, designed in 1928 by Sir Edwin Lutyens, and the Japanese Embassy, built in 1931.On the southeastern section of the row, between Scott Circle and Dupont Circle, many mansions were replaced by larger office or apartment buildings between the 1930s and the 1970s. More recently, several prominent think tanks have clustered in that area.