The monuments resemble large stone towers with oversized caps on top of them (referred to as "balloons") which hold several gun turrets underneath them. Three of them can be found in the following locations around Bygon Island:
The monuments serve as an ancient defense for Bygone Island. When activated, their balloons are release and will float into the sky, giving them an ideal position from where to use their weapons against invaders. Meanwhile, the towers produce a pillar of light connecting with their balloons.
To complete the mission, the player has to go to each of the three monuments. The monuments have rotary walls that need to be moved in order to activate the tower. To do so there are three Enerbeam switches that, when pulled, will turn the tower walls to reveal three green buttons. Once the three buttons are pressed, the monuments will release its balloon, allowing it to float into the sky.
- Perci regards them as ancient monuments. Whether she means they were constructed by the Ancients or to be taken literally, is unconfirmed.