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The structure of a mosque is simple and it expresses openness. Calligraphic inscriptions from the Quran decorate mosques and mausoleums in Punjab. The inscriptions on bricks and tiles of the mausoleum of Shah Rukn-e-Alam (1320 AD) at Multan are outstanding specimens of architectural calligraphy. The earliest existing building in South Asia with enamelled tile-work is the tomb of Shah Yusuf Gardezi (1150 AD) at Multan. A specimen of the sixteenth century tile-work at Lahore is the tomb of Sheikh Musa Ahangar, with its brilliant blue dome. The tile-work of Emperor Shah Jahan is of a richer and more elaborate nature. The pictured wall of Lahore Fort is the last line in the tile-work in the entire world.

What color tile was used in Ahangar's tomb?
blue