The rabbis classified Kiddush Levanah, the monthly blessing of the moon, as one of the small but weighty acts of avodah, service of Heaven. The Kitzur Sh'lah and the kabbalists preserved specific customs around it.
It is a meritorious act, the tradition teaches, to bless the moon at the close of Shabbat, dressed in one's finest garments and perfumed, as if going to greet a king. If the blessing must be said on an ordinary weeknight, one still wears one's best clothing.
The kabbalists disputed the timing. According to the mystics of Safed — the school of Rabbi Isaac Luria in the 16th century and the earlier authorities of the Zohar — the blessing is not recited until seven full days after the new moon's birth. According to later halakhic authorities, three days suffice.
But here is the detail that most interests the tradition: the blessing is never said indoors. One must step outside, under the open sky, to see the moon itself.
Why? Because to bless the moon is to greet the Shekhinah, the indwelling Presence of God, whom the mystics associate with the moon's reflected light. And it would not be seemly, the rabbis ruled, to receive the Presence under any roof other than the roof of the sky. You do not usher the Queen into a back room. You go out to meet Her in the courtyard of the world.