Grain silos were the hallmark of Joseph
Joseph built silos to store grain in key Egyptian cities. If one was to look for some lasting legacy of Joseph in Egypt that is mentioned in the Bible, it would be grain silos. Similarly if one was to look for a lasting legacy of the Israelites in Egypt, it would have to be mudbricks, and lots of them. These are the two things that the Bible mentions that could have stood the test of time and are unique enough to positively confirm the existence of Joseph and his family in ancient Egypt. Joseph was the first to think of building grain silos in Egypt and so naturally, one would look for the oldest grain silos to be built in Egypt.