This is the ruined city of the Kingdom of Golkonda (c. 1364–1512) which has several curious acoustic features including what has been described as an “amazing clapping telephone”. Clap near the entrance, and sound is reflected by a nearby building so that it can be heard a kilometer away at the highest point of the city, at the Bala Hisar pavilion. Some other quirk of this “magical acoustic system” means that close to the person clapping, the sound can only be heard within a few metres.
11 km west of the city of Hyderabad, Andhra Pradesh state, south-central India. Suggested website for more information.