What Is The Significance Of The Dome (inside)and The Fountain Piece (outside) At The Mosque?

Actually the dome and the fountain have been historically associated with Mosques all over the world. The fountain piece was outside the building of mosque because people would perform "Wudu" or ablution - a basic ritual before performing Namaz or Salah, outside the mosque. This would maintain the sanctity of the Mosque and Muslims could make use of the fountain outside to meet their basic requirements. On the other hand Dome has also been an intrinsic part of the Mosque Architecture. The theory behind it could be that there were no loudspeakers in the past. A dome in the Mosque would allow the voice of the Azan ( call for prayer) to reach the nearby areas. So that people would know that its time for prayers.