Since this paragraph is all about posters, we'll stick to a wide overview of paintings and photos of subjects and places from long ago. "Ancient" images and artifacts -- usually masks, pottery, cave drawings, and architecture -- typically date before the end of the Western Roman Empire, around 475 AD.
So far, the oldest European art can be found in France's Grotte Chauvet, whose walls display drawings and engravings from 32,000 years ago. In America, the oldest art was carved some 13,000 years ago on the bone of a mammoth. Today's digital prints and posters make it easy to surround yourself with high resolution ancient art from the past.