From Freep.com:
POLICE HISTORY ON WEB: Detroit crime buffs can take a peek at precinct history on the Detroit Police Department's Facebook page. Decades-old photographs of precinct buildings -- some of which were built in the late 1800s -- were posted on the social networking site Thursday. Many of the buildings have been demolished. The site photos are at http://www.facebook.com/detroitpolice.
More specifically, they must be referring to Detroit Police Department's Photos. There's not much material there yet.