To what extent is a rebuilt monument still classified as historical monument?

After finishing term 2 critical reading classes, we need to write an essay which is a critical reading essay. Based on three materials we have read to make our own argument and the three materials are weather architecture, occupying architecture and literal and phenomenal. In this essay, I will use 2 projects Barcelona Pavilion (in weather architecture) and Da la war Pavilion as examples to discuss for the whole essay.