The cosmology of Edda consists of a celestial plane of Heaven and an infernal plane of Hell. Heaven and Hell are physically linked to Edda, Heaven just above the cloud line and Hell just below the world’s crust. Travel between is possible simply by climbing a tall mountain or descending a deep cavern (as well as many others). Entrances to each are guarded by powerful angels and devils, respectively.
Edda’s Heaven is strongly good-aligned, and contains within it a demi-plane for each ethical axis: lawful, neutral and chaotic. The demi-planes match those of the Great Wheel cosmology in the core D&D game.
Edda’s Hell is strongly evil-aligned, and like Heaven it contains demi-planes for each ethical axis, matching those of the Great Wheel.
Edda’s cosmology also consists of a coterminous Shadow Plane and Limbo. All spells and effects using the Ethereal Plane instead use the Shadow Plane.
Edda has a similar calendar to Earth, with 365 days each solar year (no leap year). The calendar is otherwise identical to the calendar of the Forgotten Realms.