A remarkable signaling device had been incorporated in the construction of Golconda Fort at Hyderabad (India). The various edifices are so placed as to transmit sound to different far away points. If one stands at the center of the entrance portal (the dome near Fateh Darwaza) and claps the sound is deflected by the opposite building, which is constructed at an angle to the entrance. In this manner, sound will be carried to the hilltop (Bala Hisar pavilion) which is more than a kilometer away, although at the other close points it may not be heard. This fantastic acoustic effect is a result of reverberation of sound and served to alert the royal dignitaries.