New York Public Library, St. Agnes Branch

The poshly redone Upper West Side branch, one of 67 city libraries built with funds from Andrew Carnegie in the early 20th century, has its children's room on the ground floor rather than upstairs, underscoring the importance with which St. Agnes takes kids. The feelings are apparently mutual: Children's librarian Dina Brasseur's storytimes, held in an enclosed room on the third floor, are so popular that parent-child pairs must stop in beforehand to secure tickets—and they go fast.