ShotHotspot has mapped 13 abandoned places in Allen, Indiana, ranked by how often they're photographed, viewed and voted for. The most popular are Drafty Factory Abandoned Adventure, Abandoned Playground Expirimental Sno and Sand Volleyball Tourney Rain. Some are private property or unsafe, so get permission before you visit.
We don't know whether you're allowed to visit any of these places. Many are private property, closed to the public or unsafe: get permission from the owner or the relevant authority, and take safety precautions.