I thought encyclopedias were a comparatively modern invention, but there is the Suda:
(Σοῦδα or alternatively Suidas Σουΐδας) is a massive 10th century Byzantine Greek historical encyclopædia of the ancient Mediterranean world. It is an encyclopædic lexicon with 30,000 entries, many drawing from ancient sources that have since been lost. The derivation is from the Byzantine Greek word suda, meaning ‘fortress’ or ‘stronghold.’
Alexander Pope knew about the Suda and said in the Dunciad, “For Attic phrase in Plato let them seek, / I poach in Suidas for unlicens’d Greek.” (4.227-8) The Danish scholar Ada Adler made a critical edition of the Suda in the 1930s, which we can now consult on line.
According to the Suda, Hypatia of Alexandria once rebuffed a suitor by throwing sanitary napkins at him! And some believe school and esoteric knowledge are not fun, but how is it not fun to learn of these exciting rumors?