Chicago’s bridges are internationally famous and celebrated locally, except perhaps by those waiting in traffic when a drawbridge is raised. “They’re part of the fabric of our city,” said Margaret Frisbee, executive director of Friends of the Chicago River, which operates the McCormick Bridgehouse & Chicago River Museum downtown. “Chicago is here because the river is here, and the bridges tell the story of our history and how it evolved.” That includes the engineered waterways that created links between the Great Lakes and the Mississippi River system, such as the Cal-Sag Channel.