Java Edition:Structure Files
Structure files were files generated in the data folder within the world save folder that stored information about their respective structures' locations and bounding boxes.
Obtaining
In 1.6.3 Pre-1 (1.6.3 on Minecraft Wiki), structure saving was added to store their information properly across different versions. This change was made on a time basis, and not a version basis. This means that while it was changed in 1.6.3 Pre-1, there are a few 1.7 snapshots that do not contain these changes. This makes two version paths, 1.6.3 Pre-1 through 1.6.4, and again from 13w37b through 18w05a. These files generate within the data folder of the world save folder whenever one of these structures is marked for generation (file path <world>/data/<structure>.dat). The variants of the structure files are Village.dat, Fortress.dat, Temple.dat, Mineshaft.dat, and Stronghold.dat. Later, in 14w25a, Monument.dat was added, in 15w31a, EndCity.dat was added, and in 16w39a, Mansion.dat was added. The structure save format was changed in 18w05a to store bounding boxes and structure locations directly within the chunk's data, making the structure files obsolete. They remain in the data folder, but do not do anything.