Gruta Casa de Pedra (SP-009) is a cave located in the karstic region of the Alto Ribeira Tourist State Park, between the municipalities of Apiaí and Iporanga, to the south of the State of Sao Paulo, Brazil.[1] It is 2,930 meters long and features the largest cave mouth in the world, measuring 172 meters high.[2] It is located in the final portion of the hydrographic sub-basin of the Maximiano stream which enters the cave for about 800 meters and flows into the Iporanga River.[3] Its name derives from the size of its portico, recognized as the world's largest.