Old Sewer Manhole
Hm… A mysterious 12-foot object in the middle of nowhere. Where have we heard this before? Oh, right, the monoliths that appeared out of nowhere and suddenly vanished. However, since this thing was made of bricks and mortar, it was pretty clear that it didn’t have any hopes of just getting up and leaving.
After asking people online, the OP learned that this was an old sewer manhole. According to some people, it’s no longer in use, but knowing what it was used for in the past, it’s best to leave the brick building alone. Probably stay 30 feet away from it at all times to avoid the smell.