Worth visiting for its architecture alone, the 1906 personal library of Pierpont Morgan, the late 19th-century industrialist, was designed by Charles McKim of McKim, Mead and White. It's clear that no expense was spared—beneath an ornately painted ceiling, literary types will marvel at three tiers stacked with texts, as well as Thoreau's Walden Pond journal and preliminary sketches from the children's book Babar. Music lovers can peruse original manuscripts by Beethoven. A gallery upstairs in the Renzo Piano addition—an airy glass-and-steel structure completed in 2006 that unites three historic buildings—houses more adventurous special exhibits, compared with the somewhat staid permanent collection. A 2006 show focused on Bob Dylan memorabilia and other folk-music artifacts.