Explanation:

Qila-i-Kuhna Masjid: This mosque, found inside the Purana Qil'a of Delhi, was built by Sher Shah Sur (r. 1538-45) during the interval of Sur dynasty rule. It is a large, single-aisled mosque that would have served as the sultan's Jami, or Friday mosque. It is an early example of the extensive use of the pointed arch in the region. It is richly decorated, with calligraphy, colored stones, and elaborate carvings on both the exterior and interior surfaces. The mosque was greatly admired by the Mughals, who were to look to it for details of ornamentation and construction.