770 Eastern Parkway (Hebrew: 770 איסטערן פארקווי), also known as simply "770", is the street address of the central headquarters of the Chabad-Lubavitch Hasidic movement, located on Eastern Parkway in the Crown Heights section of Brooklyn, New York, in the United States. The building is the center of the Chabad Lubavitch World movement.
The building originally served as a medical center, but it was closed down by officials after they discovered that illegal abortions were performed on the site. In 1940 it was purchased by Agudas Chasidei Chabad and adapted for the needs of Rabbi Yosef Yitzchok Schneersohn. Rabbi Schneersohn was paralyzed and required a wheelchair when he arrived in the United States in 1940. A building with an elevator needed to be purchased for his use as both a home and as a synagogue. After 770 was purchased, the synagogue was given the name "Congregation Lubavitch". The Crown Heights neighborhood was chosen as the air was felt to be better for the Rebbe's ailing health.
Importance of 770:
Rabbi Menachem Mendel Schneerson described 770 as "Beis Rabbenu ShebeBovel" ("house of our teacher in Babylon"), "And we may explain, according the above, that as regards 'our teacher's house in Babylonian' in this generation-it means the home and synagogue of my holy father-in-law, the leader of our generation... 'Our teacher's house' is the primary 'little Temple' in this last exile ... which is the place of the future Temple itself, and not only that, but there will be revealed the future Bais Hamikdash, and from there is will go to Jerusalem. This idea is suggested in the name of 'our teacher's house' in our generation: ... it is universally referred to by its number, 770, which has the same gematria as paratzta (you will spread out)."
Zalman Jaffe was a lay leader in Manchester, England and had a very close relationship with the Lubavitcher Rebbe, in his book "My Encounter with the Rebbe", he relates that, "I found a Tehillim in 770 which, on the front piece, was inscribed, 'The gematria of Beis Moshiach (the house of Moshiach) is 770.' I showed it to the Rebbe who laughed heartily." Later the Rebbe himself pointed out this gematria in a footnote in the famous "Kuntres B'inyan Mikdash Ma'at".