Treasure hunter
Once he spotted the geysers, Lex flew high into the sky to get a good view of the entire region. With a birds eye view, he finally realized why he hadn't been able to tell there was an entire city here when he received information about the whole realm.
The leopold had built their city in a way that incorporated nature into their construction style. They were not worried about wasting space if a clump of trees couldn't be worked with, or a specific region had a river running through it. They instead adapted their construction to the natural contours of the land. They had managed to keep alterations to the land to a minimum, which was quite impressive.