The Pettit National Ice Center is one of the United States' major speedskating venues, with Olympic training associations and large indoor ice facilities. For Milwaukee, it adds a serious winter-sports landmark to a city better known for beer, lakefront festivals, and baseball.
Public skating makes it accessible even if you are not following elite competition. Check session times before going, then enjoy the novelty of skating in a venue built for athletes who move far faster than the rest of us.