Wis. Stat. § 229.11: First class city museums.

Any city of the 1st class however incorporated may establish and maintain, for the free use of the inhabitants thereof, a public museum for the exhibition of objects in natural history, anthropology and history, either the several or any one of these specifically; and may receive, hold and manage any bequest, donation or loan for the establishment, increase or maintenance thereof, under such regulations and conditions as may be prescribed pursuant to law or agreed upon by and between the donors and said city.