The Sidi Saiyyed mosque, built in 1573, is one of the most famous mosques of Ahmedabad. The mosque was built by Sidi Saiyyed, who was a slave of Sultan Ahmed Shah.
The mosque was built in the last year of the Sultanate of Gujarat. The mosque is entirely arcuated. The mosque has ten screen windows (jalis) on the side and rear arches. The two bays flanking the central aisle have reticulated stone slabs carved in designs of intertwined trees and foliage, a palm and parasite motif. This intricately carved stone window is called the Sidi Saiyyed Jali.
Info taken from wiki here