Callao Cave

     Callao Cave is a cave with seven chambers located on the Province of Cagayan, in the Philippines. It is one of the best known tourist attractions of the province. It is located in Barangays Magdalo and Quibal, Peñablanca, near Tuguegarao City, the capital city of the Province of Cagayan.
It has a natural cathedral located at the first chamber, which was turned into a chapel by the local people. The conditions inside the cave cause stalactites and stalagmites, particularly in the deeper chambers.
Every chamber has natural crevices, which let light get into the cave, serving as illumination for the otherwise dark areas of the place

http://en.wikipedia.org/wiki/Callao_Cave