About 15 km. west of Agra sits the tomb of Akbar, the 3rd Mughal emperor. Same basic plan as other tombs in northern India. Gates. Garden. Plaza. Pretty ornate, and a lot of attention paid to harmonics. Sound harmonics. In the room containing the cenotaph sounds at certain frequencies bounce around forever. One man makes a living from baksheesh just to stand there and hum at the best frequency. Some of the outside chambers work similarly. Stand at one column facing away, and someone standing at another column will hear you as if you are speaking right into their ear.