Carnegie Library of Pittsburgh
The main library (pictured) and 18 branches of the Pittsburgh public library system are Carnegie libraries, and they were the first ones to use Carnegie's open-shelf policy, which we still use today, where patrons help themselves to books from the shelves. The Pittsburgh libraries were first in line for another library revolution, too: the circulation desk. To prevent theft, libraries stationed huge circulation desks near the front doors as a barrier for would-be thieves. Years later, a manager of Pittsburgh's Homewood branch dubbed this front desk design "the battleship."
Architecture critic Patricia Lowry once wrote, "To this day, Carnegie's free-to-the-people libraries remain Pittsburgh's most significant cultural export, a gift that has shaped the minds and lives of millions."