The Chaos Temple (AKA Zamorak Temple) in the Wilderness is a Temple of Zamorak located around level 14 Wilderness, north of Varrock. The temple is accessible only from the north, as the entire building is near-completely surrounded by molten lava.
It contains an altar which may be used to offer bones for Prayer experience. Using bones or ashes on the altar gives 350% of the Prayer experience that would be gained by burying or scattering them, equivalent to the Prayer experience bonus given by a gilded altar with both incense burners lit. But unlike a player-owned altar, modifiers such as Bonus XP and the First age outfit do not work here. After completion of the hard Wilderness Tasks, Harrison, who is located at the Chaos Temple, will un-note noted items for the player.
The contains many spawns of bones. Free players may use these bone respawn points at a lower prayer level to raise Prayer, especially if the player has low combat and cannot efficiently raise prayer from killing big bone dropping monsters such as hill giants. There is a trapdoor behind the altar that is part of the Defender of Varrock quest.
The pattern on the floor hints that the temple may once have been dedicated to Zaros, which is plausible given that many of his fortresses and outposts in the second age were in what is now the Wilderness, and were destroyed and/or aligned to different Gods during and after the God wars.
During the Third Age, was a Zarosian temple as shown in the "Saradomin Strikes" campaign. Several gods, such as the Menaphite Pantheon, Saradomin, Bandos, Zamorak and Zaros fought for the treasures kept in the temple.