Monument building can occur when someone places a tile. There are six monuments in the game. Each monument consists of two different-colored parts; be sure to assemble these in the correct configuration.
If the active player places a tile in such a way that he creates a 2x2 square of four like-colored tiles, he may flip those four tiles facedown and place a monument on top of them. One color of the monument must match the facedown tiles. If that color is no longer available, the monument cannot be built, and therefore the tiles cannot be flipped facedown. â€¦