- "We can roam the bloated stacks of the Library of Alexandria, where all imagination and knowledge are assembled; we can recognize in its destruction the warning that all we gather will be lost."
– Alberto Manguel
In the base game, the Great Library is one of the worst wonders in the game. It is unlocked by a late Classical Era civic and grants Eurekas to all Ancient and Classical Era technologies, which most likely are already boosted or available to you. Its other bonuses are way too insignificant to justify its Production cost. Theoretically, the only situation in which the Great Library is worth it is when a civilization has strong Culture and has managed to unlock it relatively early, but is lagging severely in tech development. This situation, however, is vanishingly rare: you always start with more Science per turn than Culture (except when playing as Trajan or Babylon), the Campus is unlocked way before the Theater Square, and the Eureka for Writing is almost always guaranteed while the Inspiration for Drama and Poetry is hard and expensive to obtain. The greatest use for this wonder in the base game is the 2 Great Works of Writing slots (which help cultural civilizations more than scientific ones), but still, it should almost always be at the bottom of the priority list.
From Rise and Fall onward, the Great Library provides a random tech boost every time another player recruits a Great Scientist. This is particularly helpful if you're playing as a Culture-focused civilization, since the Great Scientists your opponents recruit will help you advance through the tech tree faster as you develop your Culture and Tourism foundation. As in the base game, however, it proves practically worthless when playing as a Science-focused civilization, since you'll most likely be getting the majority of Great Scientists and won't receive the extra Eureka for doing so. Even China, who on paper may get more out of the Great Library than most due to their boosts being 60% rather than 50%, should not build it unless they are going for something other than a Science Victory (most suitably, a Cultural Victory).
On the other hand, Babylon should make building the Great Library a priority, as it immediately gives them every single Ancient and Classical Era technology, which is huge considering their low Science per turn. With Rise and Fall, they also get free technologies from it in the late game, which immensely helps them on their quest for a Science Victory.
It is generally assumed that the Royal Library of Alexandria was founded at the beginning of the 3rd Century BC during the reign of Ptolemy II after his father had built the Temple of the Muses on the site. The original collection is attributed to Demetrius Phalereus, a student of Aristotle’s (supposedly the famed philosopher’s own scrolls served as the seed); with the patronage of Ptolemy’s successors, the holdings eventually reached between 400 and 700 thousand papyrus scrolls and various vellum codices. Expansion of the collection became an obsession for some of the rulers; by decree of Ptolemy III, all visitors to the city had to surrender any writings in their possession, which were copied for the Library. Sources differ widely on responsibility for the fiery destruction of the Great Library’s collection of texts; usual suspects listed include Julius Caesar’s troops in 48 BC, Roman Emperor Aurelian c. 270 AD, and others. But it does appear that the last vestiges were burned in 391 at the orders of the Patriarch Theophilus to eradicate pagan influences in Egypt – not the last time Christians would burn books.
Greatest Is As Greatest Does