Iowa State University’s Parks Library was “the finest piece of architecture in the state,” said Raymond A. Pearson, the university’s president, when the cornerstone of the library was laid in October 1923. Today, the library is much larger than its original 176 by 130 foot, or 35,000 square feet, blueprint. It’s now 325,488 square feet and home to more than 2 million books. A centennial celebration event will take place on Wednesday, Sept. 24,