How do I arrive at the cost basis of a rental property that was purchased in 1996 but never depreciated in order to calculate the capital gain after an insurance settlement due to a fire?

Just wanted to add that when Form 3115 is filed (i.e. the change of accounting method is effected), the catch-up depreciation (prior years') is a deduction line item under "other deductions" on Sch E.  The current year depreciation is deducted on the "depreciation" expense line.  The accumulated depreciation, and thus adjusted cost basis, will then be all caught up.  

If NO Form 3115 is filed, the adjusted cost basis would still be the same - because the recaptured depreciation is the higher of the "allowable" and "allowed" amount.  Just that by filing Form 3115, the tax benefit of the "allowable" depreciation - the prior years' - can be realized in one (the filing) year, instead of being lost in the vacuum. 

So true.  Yet, don't forget, I come here only for kicks and drama.  So, I'm okay with it.

@dkh: Your comment reminded me of an old joke.  Little boy walked into the kitchen and asked, "Mom, what's sex?"

Mammy sat him down, started with bird and bees and butterflies...  A good twenty minutes later, little boy interrupted her and asked, "How can I put all that in the little boxes - one box says M, the other says F?"