Or learn Hittite. It's got the oldest corpus in the Indo-European language family. You've got your standard assortment of Indo-European cases. Grammatical gender is animate/inanimate and the animate gender has yet to split into masculine and feminine. The script is tons of fun, especially if you write it with a stylus on clay. And as a bonus, you get to learn a smattering of Sumerian and Akkadian vocabulary.