ruins is a mod that aims to increase the number of structures generated in a Minecraft world. These new structures will mostly look dilapidated and abandoned, but not all of them will look like that, others will be more like complete structures, like hot air balloons, ships, houses, and castles.
In these ruins we will find enemies, although they are not exactly new dungeons. By eliminating all the enemies in the area, we can start looking for hidden treasures, if they exist, since not all ruins or structures will find hidden treasures.