On the 12th of Av in 1940, the building at 770 Eastern Parkway in the Crown Heights section of Brooklyn, New York was purchased by Agudas Chassidei Chabad to house the living quarters, study and office, Yeshiva, and synagogue of the sixth Lubavitcher Rebbe, Rabbi Yosef Yitzchak Schneerson (1880-1950), who had arrived in New York (following his rescue from Nazi-occupied Warsaw) five months earlier.
Originally serving as a medical clinic, the building later served as the headquarters of his son-in-law and successor, the Rebbe, Rabbi Menachem M. Schneerson, and continues to be the vortex of Chabad-Lubavitch’s global network of institutions of Jewish education and outreach.
From its inception the synagogue has served three parallel purposes. It is a place of daily prayer services, a study hall for advanced students, and an assembly hall for Chabad gatherings, known as Farbrengens. Here the Lubavitcher Rebbe or elder Chassidim would address Chassidim and other visitors about Torah observance and Chassidic philosophy and practice.
As the Lubavitch movement grew in the United States, the original small synagogue was soon too small to house the growing number of worshipers and students who regularly came to pray and study there.
The synagogue was expanded in several stages. The first annex was added in 1960, with subsequent expansions taking place in the late 1960s and again in the mid 1970s. The synagogue then reached its current size. The original synagogue remains as a small study hall used by rabbinical students during the week.
In 1988, the Rebbe laid the cornerstone for a larger renovation project which is yet to be completed.