Insurance for a converted building

[Tim Johnson]

Hello BP!  I was doing some insurance shopping the other day.   We own 5 multifamily buildings.  Insurance rates for 4 of the buildings are "reasonable". 

The fifth building is an older all-brick building.  It was originally a school building and converted to a multifamily (10 units) around 40 years ago.  

My insurance broker can only find 1 company to insure the building, and their rates are very high.  My broker claims they cannot get other insurance because this is a 'converted structure'.  

Does anyone have any suggestions about getting other insurance companies to quote the building?  The electrical is all updated, we've done new smoke detectors and fire extinguishers.  The walls are about 2 feet think, so the building seems indestructible to me.  I'm not sure why the fact that it was once a school-house matters?  Or (more importantly) how to get a better insurance rate despite the building's history.