Sketch of an infinity pool on the rooftop

Quick answer：

An infinity pool on the rooftop is a design feature where the pool extends over the edge of the building, creating the illusion of water flowing to the horizon. This design often incorporates a vanishing edge, where the water level appears to drop off, blending the pool with the landscape. It is a luxurious and visually striking addition to high-rise buildings, offering residents or guests a unique vantage point for relaxation.