The World Tree
In the first Thor movie, they showed that ancient Norse gods and mythology hadn’t just gone up in smoke. The gods just stopped visiting the planet after a tiny town in Norway became the battlefield between them and the Frost Giants.
Later on in Captain America, the same village in Norway became the next stop for a raid of Hydra under Red Skull’s commands. In this unassuming town, he finds a mural of the mythical tree Yggdrasil, an integral part of Nordic mythology. Odin had kept the Tesseract behind the World Tree to keep it hidden.