What is the oldest tomb stone you've ever seen?

In Dallas downtown they have an old cematary where many of the founders were buried there.It is right in front of the city hall.I was looking at them and there were lots of people from the era you are talking about.Many only lived until their 40s and 50s.Some of the stones are wore down by weather and are unreadable but for the most part ya can see the dates and names