The Riverwalk runs through Downtown and the Third Ward along the Milwaukee River. Bar hopping along it is fun, but that costs money, so stick to sightseeing the architecture, public art, and interesting people all along it.
The Mitchell Park Domes are free to MKE County residents every Monday before noon. The desert and tropical domes are the best, because the third one rotates with the season and somehow it’s mums 80% of the time. Don’t touch the cacti.
Both the Milwaukee Public Museum and the Milwaukee Art Museum are free the first Thursday of every month. While art is cool and all, you must walk the Streets of Old Milwaukee and find the rattlesnake button at the MPM if you haven’t already.
Every Sunday. Free bacon. No-brainer.
One neighborhood in West Allis comes together after Thanksgiving and goes so nuts with holiday decorations that you can probably see it from space. It’s for charity, so while it’s technically free, you should probably not be a total cheapskate here.