Hi! You can just write : These books went back 500 years. An antique is a subjective word. It's an object that has been given a value as an antique and a financial value. Some old objects aren't antiques. Ancient means "very old" (a museum piece) From several centuries ago. "Old" means "old" - this could even be a book from 1970.

They are slightly different. Antique is probably anything older than 100 years or so (the date is probably quite specific, but I'm not in the trade to know) so would substantially underestimate the age. Ancient is probably quite appropriate for that sort of age. Old is very 'generic'. It could be anything, and isn't very specific. Here it might be as little as 30 years.

Ok now I see it is about the time. Sorry I was wrong.

Or perhaps something like - 'books, some of which date back to the founding of the library' or something like that.

So maybe I should omit the adjective then?