Here 's a familiar and effective design trick often used at theme parks: Corral guests under or through a passageway that forces the crowd to narrow before a grand reveal. Think of Disneyland 's Main Street, U.S.A., where park goers are shunted through a passage under a train tunnel that gives way to a romantic, turn-of-the-20th-century town and a fantastical castle. At the entrance to Disney ...