First of all, your sentence is passive. because THE SCHOOL is not alive and it itself can not go somewhere to stay there and choose that place as its location. So your sentence is Passive.
but in my oppinion, located is verb. when ever you want to understand if a word ids verb or adjective, use this method.
for example , ask your self if ( locate) is an adjective for ( school) or not. of corse ( lacate ) is not an adjective for school , but if we want to think about it as a verb , it will come true. if we omit the two words ( is located ) and replace it by ( Is ) or ( places) , there will be no problem with the sentence. so, is+located have only one function, both of them with each other. they are used as a verb phrase.
send me a private message if you are not satisfied yet.
Hope that helps