The Callao Cave system has seven chambers, with natural crevices above to let streams of light into the dark areas. An earthquake in 1980 cut off the last two caves that had previously been part of a larger network.

The first chamber has a cathedral-like feel, and is used as an improvised chapel by the locals. It’s also the largest of all chambers—a large rock formation serving as its altar gets lit up from above when sunlight streams in through an opening in roof.

The Callao Caves can be visited by experienced spelunkers or caving enthusiasts on guided tours, although some portions may be closed seasonally or permanently for conservation purposes.

Analysis of the sediments and deposits within the cave has definitively identified human occupation dating back at least 67,000 years B.P., indicating that this site was only intermittently occupied during its 77,000-year history.

In 2007, Callao Cave fossils dating back to the Late Pleistocene period were discovered by a team of Filipino, French and Australian archeologists led by Armand Salvador Mijares from the University of Philippines; they were eventually identified as belonging to an extinct human sub-species, Callao Man or Homo luzonensis in year 2019.

It was found to be at least 67,000 years old. The discovery of this fossil, which predates all previous finds from the Philippines (including those from Palawan Tabon Man), represents the earliest evidence of human occupation in Southeast Asia. The find is the oldest human traces ever found in all of Asia-Pacific, adding a new chapter to the complex history of human evolution.