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Civilization 5 World Wonders: Great Library
Building Strategies and Wonder Information
World Wonder: Great Library
Tech Required: Writing
Production Cost: 185
What it Does: Free Great Scientist, +3 Science, 2 Slots for Great Works of Writing. Free Library in City, saving you maintenance costs. Also gives +1 Culture and +1 Great Scientist points.
Reportedly almost unbuildable on Deity Difficulty, this is one of the most popular Wonders to build because of its early free Tech (allowing you to grab Philosophy, Drama and Poetry, Iron Working or another high-value tech). The Great Scientist is also invaluable at this stage of the game because it is perfect for an Academy to boost a City's Science output for the entirety of the game. You'll also be set to get another Great Scientist within 100 turns.
A strategy used to pass the enemy in Science, while suffering in the Land and Population areas is to go Tradition, focus on Writing then rush this Wonder to then get Philosophy and a National College before you place your first Settler. This saves you a lot of turns getting out that second Library, but the National College costs even more production than the Great Library itself - for good reason. A city putting out 32+ Science at that stage of the game is super powerful and will ensure you get to the next Wonder you intend to build faster than your opponents.