Bears

George Halas and Edward "Dutch" Sternaman built it in 1919 as the Decatur Staleys, sponsored by a starch manufacturer, and only brought it north to Chicago in 1921, taking the Bears name a year later once the league had settled on its permanent form as the NFL.

The nickname that stuck to them, Monsters of the Midway , was borrowed from the University of Chicago's football team before the Bears took it over in the 1930s and 1940s, and it found its truest expression in the 1985 defense, which carried Mike Ditka's side to a 15–1 season and the club's only Super Bowl win. Before that era, championships came the old way: eight NFL titles between 1921 and 1963, won in a league that had no Super Bowl to hand out. One of them, the 1940 title game against Washington, ended 73–0, still the heaviest defeat in the league's history.

Halas himself never really left the building — he coached and owned the team for decades, long enough to overlap with Bronko Nagurski at one end of the club's history and Walter Payton and Dick Butkus at the other, names that carried the franchise's defensive and running identity well past his own playing days. The rivalry with the Green Bay Packers, running since 1921, is the oldest in the NFL and has outlasted every coach and every stadium renovation on both sides.