The Music Room on the sixth floor at the palace of Ali Qapu Palace in Isfahan is really both an aesthetic and an acoustic masterpiece, as you read here: http://en.wikipedia.org/wiki/Ali_Qapu The rooms were used for private parties and for the King's musicians, and these hollow places in the walls retained the echoes and produced the sounds of the singing and musical instruments clearly in all parts.
Miniature painting of female musicians from Hasht-Behesht Palace in Isfahan:
Music Room in Ali Qapu Palace: