Short answers, pulled from the story.
The name Agra derives from either the Hindi word agar meaning salt pan or the Sanskrit word agra translating as front. Some scholars link the term to Hindu mythology where it represents the first forest where Krishna frolicked with the gopis of Vrindavan.
Sultan Sikandar Lodi rebuilt the site between 1504 and 1505 establishing it as a seat of government on the left bank. Mughal Emperor Babur defeated him at the First Battle of Panipat by 1526 causing the city to pass from his control.
Shah Jahan gave Agra its most prized monument the Taj Mahal constructed between 1632 and 1648 in memory of his wife Mumtaz Mahal. Construction commenced with upwards of twenty thousand workers completing the mausoleum itself by 1639 while decoration work continued until at least 1647.
Control of the city fell successively to the Jats the Marathas the Mughals and finally the British East India Company. The Hindu Jats of Bharatpur conquered Agra on the 12th of June 1761 after a month-long siege before losing control again in 1774.
The white-marble Taj Mahal is turning yellow and green because of filthy air in the world's eighth-most polluted city. Air pollution caused by emissions from foundries and other nearby factories has damaged the monument's marble facade.