Andrew Carnegie was once the richest man in the world. Coming as a dirt poor kid from Scotland to the U.S., by the 1880s he'd built an empire in steel — and then gave it all away: $60 million to fund a system of 1,689 public libraries across the country.
Carnegie donated $300,000 to build Washington, D.C.'s oldest library — a beautiful beaux arts building that dates back to 1903. Inscribed above the doorway are the words: Science, Poetry, History. The building was "dedicated to the diffusion of knowledge."