In Adventure Comics #216 (July 1955), Superboy discovers that a city from Krypton fell and crashed into a jungle on Earth years ago. Greedy explorers discover it while searching for diamonds along with a cache of kryptonite.
Superboy has only one ally, a professor of archaeology, who helps Superboy by pretending he is Superman. Lucky that Superboy knew how to crush birch bark until it is pliable enough and then die it the proper colors…
The professor is not affected by the kryptonite and is able to fool the greedy diamond hunters. Then Superboy destroys and burying the city full of technological wonders because… ?
It turns out the writers had one trick up their sleeve though, it turns out that the professor’s name is Professor Olsen, and that’s right – his young son is Jimmy Olsen, Superman’s future pal. Meaning that this is the first time the two characters meet, chronologically.