How to report involuntary conversion of commercial property taken for conservation; original basis not known.

I am the last surviving former owner of a commercial property which was taken for conservation under the Pennsylvania Blight Act.  My brother was managing the property, but fell ill during COVID; the Borough pulled  the wrong deed and took the property without notifying me.  I only found out after the conservation and sale were complete.  All records of the original costs, etc. were destroyed during the conservation.  My questions: 

1)  Where do I report this involuntary sale of real property?  

2) How should I figure the gain or loss?  I received only pennies on the dollar due to the fees charged by the Borough and their Conservator.  There are court records of offers to buy the property, and also an independent retrospective professional appraisal.

3) Can legal fees be deducted from any gains?