This is one of the pieces from Printable Scenery's
Ancient Ruin set, along with a lich or something from
Reaper WotC (?).
I don't really use a lot of this sort of terrain in our D&D games, and I'm not a fantasy wargamer, but I do like making and decorating things like this. It's printed in PLA at 0.2mm layer height on my Ender 3, painted in a variety of acrylics, and with fine foam flock to represent moss between the flagstones and what-not.