The James S. McDonnell Prologue Room, located at the Boeing Company in the Building 100 office center at Lambert Field, offers visitors a tour of aviation firsts. It is open to the public free of charge from 9 a.m. to 4 p.m. Tuesday through Saturday through August. Reservations are not required, but groups of 20 or more or asked to make arrangements at least three days in advance by calling 314-232-6896.