Short answers, pulled from the story.
Mehr-un-Nissa arrived in the Mughal court as the fourth child of Asmat Begam and Mirza Ghiyas Beg. Her parents had immigrated from Persia before settling into imperial service under Emperor Akbar. She became the most powerful Mughal Empress after marrying Jahangir.
Historical records indicate the project began well before her death and took four years to complete at the cost of Rupees three lakhs. Much of the structure was probably built while Nur Jahan herself was still alive. The financial support likely helped fund the ambitious building project following Shah Jahan's ascent to the throne.
During the occupation of Lahore by Ranjit Singh's army, the site suffered severe damage in the 18th century under the Sikh Empire. Ornamental stones and marble were stripped from the tomb for reuse elsewhere and much of this material ended up decorating the Golden Temple in Amritsar. This event significantly altered the original appearance of the monument.
The British constructed a railway line between the tombs of Asif Khan and Nur Jahan which interrupted the open fields that had separated the monuments. The physical separation caused by the tracks remains a defining feature of the site today. Engineers later attempted to mitigate the damage through structural reinforcements.
A platform measuring 158 square feet supports the entire structure which measures 124 feet on each side and stands 19.6 feet high. Unlike her father's white marble tomb, this mausoleum is primarily clad in red sandstone with seven vaulted arches covered with marble and flower mosaics in semi-precious stones.
The central vaulted chamber contains a marble platform holding two cenotaphs one commemorates Nur Jahan and the other honors her daughter Ladli Begum. Hakim Ajmal Khan of Delhi built the original sarcophagus in 1912. An epitaph inscribed on her tomb reads On the grave of this poor stranger let there be neither lamp nor rose.