I read a report a while back about an archaeological dig that discovered a mosaic on the floor of an old church. It was in honor of "The Chief of the Apostles and Keeper of the Keys"; in other words, St. Peter. It invoked him to pray for them! It is believed that it was made no later than about A.D. 300. If you think about it for a minute, that is stunning.
The common claim by non-catholics is that the idea of praying to the Saints was made up by the Church in the late middle ages (around A.D. 800). This blows that idea out of the water. Certainly we have references in the Scriptures that point this out to us, by protestants deny that is what those verses mean (since they know more about the Bible than those who were first given it). This clearly shows that it was not merely a late belief, or even the odd idea of a few heretics; rather it is clearly the testimony of that parish church (that would have been known to their Bishop and the other parishes!) of what "the communion of the saints" means in the Creed.
What adds to this testimony is that the report pointed out that the archaeologists were not Catholic, and their own testimony was that they would need to "look more deeply into the early Church's position on the Saints". The more people look into the past, the more they find that Church was right all along. As St. John Henry Newman said, "to be deep in history, is to cease to be protestant". Praise be to God our Almighty Lord.