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 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.
This location has been used historically as a place to mount ambushes, due to its popularity as a Prayer recharge point and as there is only one entrance or exit to the temple. This gave large groups the advantage over players trapped within the lava moat, as it was difficult to escape a deliberate attack by running. Many people will attempt to lure lower levels to the temple, for things like "Drop parties". As it is only level 14 wilderness, it's easy to teleport away if you happen to have a tablet or the runes. The best thing to do is to never go to the temple unprepared for an attack. It was also a very popular place for 'death matches': a set battle between two individuals with certain rules and handicaps.
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.
High Combat level players usually go to the Boneyard because of its faster experience due to big bone spawns. However, it is located in Wilderness levels 26-29, has aggressive skeletons, and no prayer altar.
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.