Kiddush Hachodesh ("Sanctification of the Month")

The Rebbe recites Kiddush Levana, Sanctification of the Moon, in front of his home on President Street.

In chapter twelve of Exodus, G‑d gives the Jewish people their first mitzvah: “sanctifying the month”—to establish the calendar based on the lunar cycle (the rebirth of the moon). Why is this the first mitzvah?

The first mitzvah given to the Jewish people before they even left Egypt was to sanctify the new moon and keep a calendar. A careful study of the verse (Exodus 12:2) "This month shall be for you the beginning of months."