- Samurai (Wikipedia)
Samurai (侍) were the hereditary military nobility and officer caste of medieval and early-modern Japan from the late 12th century until their abolition in the 1870s during the Meiji era. They were the well-paid retainers of the daimyo, the great feudal landholders. They had high prestige and special privileges.
- Hollow Earth (Wikipedia)
The Hollow Earth is an obsolete concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproven, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.