Make your way to the north-east to find a Massive Stone Door followed by another one. Behind the second door you'll have to fight a boss enemy, Sandwraith Lord - Nightmare of the Desert. He is somewhat durable, but deals only little damage, so this fight usually is more like a test of your patience. In his chamber you'll also find a large Majestic Chest. When you have defeated him, the door to the north-east opens, where you will find the Eternity Altar. Click on it to insert the Scepter of Eternity - this will activate the Portal to Babylon.