Things made of stone are easy ones, of course, since they already have. The volume of those today is far higher than in any historical sites. Glass, ceramics co

Things made of stone are easy ones, of course, since they already have. The volume of those today is far higher than in any historical sites. Glass, ceramics could also survive in many conditions. Copper, I think? But just the stone/concrete infrastructure remains of an NYC would be very noticable. The volume of human remains would be wildly different too, admittedly we're getting away from just "city dumps" then.