1) In Norse mythology, Valhalla is a majestic hall located in Asgard, the realm of the gods. It is the afterlife destination for brave warriors who die in battle, where they are greeted by the Valkyries and engage in feasting, drinking, and preparing for the final battle of Ragnarok.

2) The sitcom "Friends" is known for its iconic Central Perk coffee shop, where the main characters often gather.

3) The Russian Revolution in 1917 resulted in the overthrow of the monarchy and the establishment of a communist government under Vladimir Lenin.

4) Aztec mythology, originating from ancient Mesoamerica, includes deities like Quetzalcoatl, Huitzilopochtli, and Tlaloc. It explores concepts of creation, sacrifice, and the cyclical nature of time, with intricate cosmology and rituals forming a significant part of Aztec religious beliefs and practices.