Norton Juster, who wrote one of children’s literature’s most beloved and enduring books, The Phantom Tollbooth, died March 8, at his home in Northampton, MA. He was 91.

The Phantom Tollbooth, first published in 1961, is the story of a bored little boy named Milo who, when a tollbooth inexplicably appears in his room, passes through it into a land of whimsy, wordplay and imagination. The book was illustrated by Jules Feiffer, who was early in his renowned career as a cartoonists and author. The book has sold almost five million copies, has been reissued multiple times, and was turned into an animated film and a stage musical.

Mr. Juster, an architect by trade, called himself an “accidental writer,” but he went on to write other children’s books. In a 2012 interview with CNN, he talked about the key to writing for young readers. “You have to retain, I guess, a good piece of the way you thought as a child,” he said. “I think if you lose all of that, that’s where the deadliness comes from. The idea of children looking at things differently is a precious thing. The most important thing you can do is notice.”