The city of gold is a secret level found in the temple, usually on 4 - 2. To access it, you need to purchase (or steal) the ankh in the black market. Next you need to survive until the ice caves and once you reach the level with the giant easter island head allow yourself to die in whatever way you want. You will be respawned in front of the entrance to the next level. Once you make your way through the levels, the ujah eye will activate just like detecting the black market. However, if you want to get to hell, you need to kill anubis before going to the city of gold. Every block in the city of gold is made of gold, and if you destroy them gold nuggets will pop out. In the center of the level will be an alter for anubis 2, which is much stronger than the regular anubis.