One of Borneo's many and varied natural wonders, the Niah Caves are a system of colossal underground chambers large enough to fit a couple of Notre Dame Cathedrals stacked on top of one another. They also contain some of the earliest human remains ever found in Malaysia.

The initial excavations into the Niah caves began in 1950s and '60s when evidence of human habitation in the caves was found, including cave paintings and remains. The remains were found to be a staggering 40,000 years old, meaning the natural caves have been fascinating homo sapiens from cavemen to the camera-happy tourists of today. The cave paintings were found to only be around 1,200 years old, making them nonetheless interesting, but paling in comparison to the ancient bones. 

Today, the caves are a popular tourist site owing to their awe-inspiring size and natural beauty. The entrance to the main "Great Cave" alone is dozens of meters tall, inviting metaphorical measures such as how many churches or other huge structures could fit in it. No matter how you describe the caves, it is likely that it will be tinged with a sense of wonder.