During its early years, the Adas Israel Congregation, composed of 35 families, met and worshiped in the homes of its members or in rented quarters. On August 16, 1870, the congregation's trustees, recorded in the deed as Manasses Oppenheimer, L. Abraham Nathan Gotthelf, and Leopold Oppenheimer, purchased the property at 6th and G Streets, N.W. Construction of the synagogue began in 1873. Max Kleinman was the draughtsman and J. William and Company the contractor. The dedication ceremony on June 9, 1876 was attended by President Ulysses S. Grant, Vice President Ferry, and other federal and civic officials.
The building was in continual use as a synagogue until 1907, when Adas Israel moved to larger quarters at 6th and I Streets, N.W. The property was sold to Steven Gatti in 1905 and remained in the Gatti family until 1968. After Adas Israel moved out, the building was used as the Greek Orthodox Church of St. Sophia (now on Massachusetts Avenue) and then by the evangelical Church of God.
The building itself is 2 stories, brick with gable roof, cantilevered wooden apse, cylindrical cupola, and tall unevenly spaced windows. The main interior on the 2nd floor includes original Ark of the Law. Adas Israel Synagogue is now the Lillian & Albert Small Jewish Museum.
DC Inventory: March 7, 1968
National Register: March 24, 1969