Photos taken on August 24, 2015.  Click on any picture for a larger version.

The condemned building appears to be the brick garage behind the house at 1337 E Mason.  Per the 1936 Sanborn Map, this brick building was an “Auto Painting & Body Works” with a roof full of skylights.

The WI AHI has a listing for this brick garage (link below).  Built around 1923, the building may be eligible for NRHP listing.

WI AHI listing here