From Bulbapedia, the community-driven Pokémon encyclopedia.
The Hill of the Ancients
The Hill of the Ancients (Japanese: せいれいのおか Hill of Spirits) is a location in Pokémon Mystery Dungeon: Red Rescue Team and Blue Rescue Team. It is on top of the Great Canyon. Xatu resides here, looking into the past, present, and future by staring at the sun with unblinking eyes.
Xatu is able to tell that the player is actually a human, transformed into a Pokémon. He is also able to communicate with Pokémon anywhere by using telepathy. He predicts the coming of a meteor that will collide with the world, destroying it. He creates the Teleport Gem with the aid of Alakazam and Gengar, so that the player's team can travel to the Sky Tower in order to ask for Rayquaza's help to prevent the meteor's collision. Some time afterwards, he tells the player of a "mirage Pokémon" and directs them to the Fiery Field.