Carved from dense granite, the Barabar Caves in India have mirror-like walls with a smoothness 9 times higher than modern polished granite.

The Gopika chamber has a surface that is 100 times flatter than a newly paved road.

Even though each cave has its own unique dimensions, there’s a 34.4 Hz echo produced at the Vapiyaka, Karan Chopar and Gopika chambers and 34.5 Hz at Sudama.