I don’t see it that often, but when I do see a couple use a vintage, heirloom, or antique rug at their wedding ceremony altar, I love it. The idea of creating a memento from your wedding (that also acts as decor) that can be passed down from generation to generation seems like the perfect touch.
While any rug will do (new or old), kilim rugs always have unique designs, and will look great even with wear and tear years later (perfect for giving to your grandkids!). Kilims are flat, tapestry-woven rugs that are typically from the Balkans and Pakistan. They were traditionally used as prayer or altar rugs, but have become more and more popular as decorative rugs in the states over the past decade (even Pottery Barn sells them).
You’ll find a good assortment just by googling “kilim rugs”, but Etsy tends to have the most interesting options. A couple options are below:
A photo of a kilim rug at Nathan Followill (King’s of Leon) and Jessie Baylin’s wedding ceremony, courtesy of Once Wed.