770 Eastern Parkway, commonly abbreviated to 770 or Seven-seventy is the address of the central headquarters of the Lubavitcher Hasidim.
History
Rabbi Chaim Nochum Lieberman, an investment banker and a big supporter of Chabad, bought the building at 770 Eastern Parkway as a gift for Rabbi Yosef Yitzchak Schneerson. Rabbi Schneersohn was paralyzed in a wheelchair when he arrived in United States in 1940. A building with an elevator needed to be purchased for his use as a home and a synagogue, despite its being a great luxury at the time.
Rabbi Menachem Mendel Schneerson, Yosef Yitzchak's successor and acting rebbe until his alleged death in 1994, led the movement from the building while maintaining a residence on President St., several blocks away.