Name any game that allows users to create their own content, and chances are Mario will make an appearance. Minecraft is no exception. In fact, it's exemplary.
We've seen 8-bit Mario art in Minecraft before, but now RoosterTeeth has uploaded a video of level 1-1 from Super Mario Brothers. Not only does the video show the level being played from a sidescrolling point-of-view (thanks to a co-op 'photographer'), but it also shows how the team built it.
Check it out.