How did a patron saint of Scotland come to rest in Downpatrick?

How did Saint Columba of Iona come to be buried in Downpatrick? Here's Duane to explain with a bit of legend and a touch of logic.

https://video.wixstatic.com/video/55e7d0_07a2c3f5a49c4045922d26c29fdf6eb4/1080p/mp4/file.mp4