How to Find Out Which Mod Adds a Structure You're Standing In
Run the Command Where You Stand
Stand exactly where the structure is — inside the walls, on the floor, or at the center of the build. Open chat and type /wits. The mod reads the structure data at your current block position and prints the registry names of every structure that overlaps that spot. Registry names look like modid:structure_name, so the part before the colon tells you which mod owns the structure. For example, a name starting with a vanilla namespace means it is a vanilla structure, while anything else points to a specific mod.
Read the Output
If you get no result, you are probably standing outside the structure's bounding box or on top of it rather than inside. Walk a few blocks inward and try again. Some structures have large bounding boxes that extend beyond the visible build, so even standing near the edge can work. If multiple structures overlap — common in modpacks where several mods generate in the same biome — the command lists all of them, so you can see every candidate.
Use It While Building Modpacks
This is the fastest way to attribute a mystery building to its source mod without digging through config files or world-gen JSON. Note that small features like vanilla dungeons and desert wells are not detected because they are not registered as locatable structures, so a blank result there is expected.