Multiple attestation by the four Gospel authors.
Women found the empty tomb. This is more than a little embarrassing to the men who wrote the Gospels in this male dominated culture.
Yes, that's what I thought. Is there anything independent of the Bible that corroborates these accounts? And do the accounts themselves match up? Let's see...
Mark says 3 women came and the tomb was already open with a man in white inside.
Matthew says it was 2 women, there was an earthquake, an angel moved the rock, and two soldiers were witnesses but they told everyone that the body was stolen.
Luke says it was 3 women, but one was different from who Mark says she was, the tomb was open, and two men tell them Jesus is risen.
John says Mary Magdalene visits the tomb and finds the stone rolled away. She tells Peter and "the beloved disciple", who run to the tomb and find the grave-clothes, then go home. Mary sees two angels and then Jesus, whom she does not recognize.
Now, compare that to the Gospel accounts of Jesus before Pilate. They are much more consistent there. Why? Logical answer: It really happened, and it was public record, where there's not much room for artistic license.