Journey Into Mystery Annual #1
While traveling out to Jotunheim, Thor and Loki are searching for a path leading to the land of Olympus, home of the Olympian Gods when they happen upon some Frost Giants, which Thor easily defeats in combat. However, the battle causes the ground to rupture and Thor falls into the chasm and finds himself in a tunnel. Following it to its end he finds himself on Olympus.
Also reprints several Journey Into Mystery issues.
Printed: Mar 1959
Writers: Stan Lee
Art: Jack Kirby and Vince Colletta
Cover: Jack Kirby