El Dorado, just like the legend says, is a natural wonder which is found exclusively in deep forests or jungles. This makes it quite difficult to find - while mountain wonders like Mt. Kailash and Sinai are spotted from a great distance (being mountains), to find El Dorado your Scouts have to venture into the most impassable terrain and get almost next to the wonder's tile to spot it. Of course, the 500 Image:20xGold5.png Gold reward for finding it first is well worth the trouble, especially in the early game!