What immense structure is referred to in Norse Mythology as the Yggdrasil.

The immense structure referred to in Norse mythology as Yggdrasil is a tree. Yggdrasil is an enormous ash tree that serves as a central symbol in Norse cosmology. It is believed to connect the nine realms of existence, including Asgard, Midgard, and Hel. Yggdrasil is considered the axis mundi, serving as a conduit for the flow of life and knowledge, with its roots delving into the depths of the underworld and its branches reaching towards the heavens. This mythological tree represents the interconnectedness of all things and the constant regeneration of life, making it a fundamental aspect of Norse mythology.