The Norns hang out by Yggdrasil, the tree at the center of the Norse universe.
The Norns were in change of ruling the destiny of gods and humans. The three most important Norns were Urðr, Verðandi and Skuld, which translate roughly as "Past," "Present" and "Future."
One of their other duties: They get water from the Well of Fate and pour it over Yggdrasil, so it flourishes.