What is the oldest part of the average human body and how old is it?

Given that our bodies as we have them today are not exactly the same as what we had as children or even last week, and that cells are continuously being created and destroyed, what is the maximum age that a part of our body could be right now?

Or to put it in a different way, what is the oldest part of our body?

I'm guessing that bones dont change much, but maybe they do! Its easy to think of ourselves as unchanging, but since our hair is only as old as our last haircut + how many weeks it took to grow that much, maybe the same is true of our entire body!?!?!

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).