The Dwarven Halls

Or rather the entrance to the dwarven halls.

Somewhat inspired by the game dwarf fortress, though I really don't know how anyone could make this sort of design in game. Also, although dragon riding is technically possible in game, you will never see it happen currently in vanilla because of how rare dragons are and possibly partly because they have the megabeast tag. Finally, taming in adventure mode is currently impossible.

So basically what you see here could not happen in dwarf fortress, but there is no reason it could not eventually.