The Pittsburgh Steelers of the 1970s were defined by the Steel Curtain, their stellar defensive line helmed by Joe Greene, as well as L.C. Greenwood, among others in a bit of a rotating cast over the years. At the second level, you had all-time great linebackers in Jack Ham and Jack Lambert.
Less known and acknowledged are the defensive backs, but at least Mel Blount is typically recognized. They had a number of quality defensive backs at the time, including Mike Wagner, Glen Edwards, and J.