This is a small cache hidden along the Hank Aaron State Trail. You can park along W Dickinson St, or better yet bike here! :-) This may be a difficult find in the snow. It is (unfortunately) not very friendly for wheelchairs or strollers.
The DNR owns and maintains the land along this paved trail, which used to a be a railroad track. At this spot, the trail is in the City of Milwaukee with the City of West Allis to the south starting at the fence. The large building to the south is a 357,000-square-foot industrial building once actively used by Allis-Chalmers, and then sold to Siemens AG in 1991, and finally closed in 1999 at the cost of 800 jobs. The building and 23 acres were purchased in 2003 by a Chicago based investment group for around $8 million. Currently, A/C Equipment Services, specializing in manufacturing rotary kilns and digesters, is renting part of the building. There was more recently a passenger railcar restoration company named Avalon Rail, Inc. The company was established in 2000, but was dissolved in 2019 and some assets were sold in March 2021.
Reference article: "West Allis, Wis., Industrial Building Sold to Chicago Investment Group", The Milwaukee Journal Sentinel, April 17, 2003