The Superior Dome on the campus of Northern Michigan University is, depending on how you measure, either the largest or the second-largest wooden dome in the world. The 14-storey structure encloses about 5.1 acres and serves as the home field for the NMU Wildcats football team along with a wide range of other sports and events.
Self-guided tours are possible when the dome is not in use; staff at the adjacent athletic offices will usually point you toward the public viewing gallery. It's a brief stop but visually impressive — the curved fir ceiling seen from inside is genuinely striking.