Is the sentence “While i was traveling i had seen beautiful buildings.” ungrammatical?
I think this sentence is grammatical using past perfect to describe multiple events in past
but the answer says ‘while i was traveling I saw beautiful buildings’ is correct.
Why the sentence ‘while i was traveling i had seen beautiful buildings’ is incorrect?
It isn’t incorrect (except that ‘I’ should always be in upper case). As a sentence on its own, it’s probably better with ‘saw’, but you could say something like “While I was travelling I had seen some beautiful buildings, but the new art gallery in my home town was as fine as any of them”.