Paying off Real Estate Taxes

[Dale M.]

I would like to start paying off some backed up property taxes , ( i.e., school, county,local,etc. ) that have collected over the past 4 years on a property I own.

My question is what tax bills are most important; 

should i pay the older ones first or the newest first

 and in what order, school first or county first or local

 All of these bills will be made current over a 12 month period and the total due is around $4000, so figure around 350 a month towards whatever taxes are due.

The property is located in Pittsburgh,PA

I appreciate any constructive advice, Thank You