You don’t find much larger artwork than that of Andrew Rogers… actually you just don’t. His stone based pieces are huge in scope, so large in fact that they are easily seen on Google Maps. You can’t say that about the Mona Lisa.
His pieces, which take their cue from ancient art like the Nazca Lines of southern Peru or the Westbury White Horse in England, form the largest contemporary land art undertaking in the world, forming a chain of 48 Geoglyphs around the globe. You can see more at andrewrogers.org.