Answer:
Machu Picchu, which is high as the Andes, was built by the Incas in the 5th century.
Explanation:
Non-defining relative clauses actually give us extra information. It gives extra information about someone or something. Without it, the sentence will still give a clear meaning. But it gives additional information especially about the subject.
Relative clauses actually start with the relative pronouns like that, which, whose, who, where, when.
