Identifying the main clause and subordinate clauses

I’m preparing for my exam and in one of the practice questions i have to identify the main clause, subordinate clause/s and the subject,predicate and/or adverbials. the sentence is:

"The Mausoleum has an interesting place in Greek history because it was a building that was not dedicated to the gods".

i thought the main clause could be "The Mausoleum has an interesting place in Greek history"

with "because" being the subordinating conjunction.

but I'm really struggling to identify the subordinate clause/s. is there 1 or 2? what type of clause is it and what would the subject and predicate be?

thanks in advanced