In honor of the 75th anniversary of Dr. Seuss's little-known second book, The 500 Hats of Bartholomew Cubbins, the New York Public Library is exhibiting a show of Dr. Seuss's extensive hat collection, set to travel the country after its brief, 12-day sojourn in NYC. (Did you know he was mad about hats, and an avid collector? Neither did we.) The exhibition, which will travel with Dr. Seuss's Secret Art Collection (estate-authorized work based on the master's drawings and paintings), is the first time the hats have been shown outside the Seuss Estate. All ages.