Installed a couple of years ago on the annex next to 770, this simple plaque (stating only the date that the cornerstone was laid) took the place of a controversial one that had, for many years, symbolized a major rift within the Chabad-Lubavitch movement.
After the death of the Rebbe in 1994, there arose within the movement a vocal faction that believed he was not actually dead and would return as the messiah. In 1995, when the leadership of Chabad installed a plaque around this cornerstone memorializing the Rebbe (implying he had passed away), it was immediately defaced by messianists. The vandalized plaque remained in place until 2004, when another group, under the cover of night, managed to remove it from the wall entirely.
Despite the presence of this rather inoffensive replacement, the feud between the two groups continues. Just last fall, the anti-messianist Chabad establishment, which owns the building, tried to evict the messianist leaders of the congregation, who control what goes on inside the synagogue, continuing a rather surreal spectacle that has been playing out for years now: a secular American court arbitrating a contentious religious dispute over whether or not a seemingly deceased man is actually the messiah.