This wafer-thin wooden tablet from a first-century Roman fort in the U.K. includes a heartfelt birthday party invitation.

The other side is the party invitation ... for the day of the celebration of my birthday, I give you a warm invitation to make sure that you come to us, to make the day more enjoyable for me ...

who invited her good friend Sulpicia Lepidina to her birthday party. The invitation was found at the Roman fort of Vindolanda, where oxygen-free soil helped preserve numerous organic artifacts ...