The largest megalithic site in Southeast Asia is Gunung Padang (Mountain Meadow in Indonesian), located in West Java. The site has been known by Europeans since the early 20th century, when it was mentioned in a Dutch report on Indonesian antiquities.
The site is noted for the huge rectangular stones that cover it. Beneath those stones, geologist Dr. Danny Hilman believes, is located an even more ancient pyramid. Judging from the age of the debris above it, Hilman believes that the pyramid would be at least 9,000 years old, and possibly up to 20,000 years old.
A survey conducted in 2012 carbon dated the upper layers of the site to 6,500 years, and layers 24 to 30 feet under to 12,500 years. Georadar located large chambers 45 feet beneath the surface. The site is characterized by the use of a strong cement which cannot be natural because it contains silica of a purity not found in the region. Radiometric analysis conducted in 2012 at Betalab in Miami dates this cement to between 12,000 and 23,000 years of age.
It would appear that this very old site, which dates from thousands of years before human beings were thought able to construct even simple buildings, was not only built of huge blocks of stone, but used a highly sophisticated cement of a kind that was not in general use again until the 18th Century.
Who built the site and why, remains unknown. It is by far the largest and most extensive human construction of its age ever found.