Marlene.......my niece works for the county dept that handles all of the bridges, etc. I asked her about the tour under the Detroit\Superior (I assume that is what you mean) and she said that the tour will be Saturday, May 24. She believes it starts at 9am & runs through either 3:00pm or 3:30pm. They open it up twice a year (fall and spring) and let you walk down in the old streetcar tunnels and on the viaduct under the bridge. My husband and I went last fall and it was very interesting....Pat