It's not as surprising as you might think : we have no ancient text about the ancient etruscan necropolis, nor about many large buildings or cities that awe us when we visit their remains. For example I don't think we have anything on the three republican temples of the Largo Argentina, in the middle of Rome. This tomb, here, was mostly a big mound of earth for the ancient and mostly a curiosity for the inhabitants of Amphipolis, with the lion at it's top, but many might not have known it was a tomb.