Agra fort was build by imperor Akbar in 1565. Original it is bil in red sandstone. Futher additions were made particularly by his grandson Shah Jahan, using his favorite building material - white marble. The fort was build primarily as a military structure, but Shah Jahan transformed it in to a palace.
Shah Jahans son Aurangzed took over the power killed, his brother and inprissoned his father.
In that way Aga Fort became Shah Jahans gildet prisson for eight years. Thrue the window in his cell he could see the mausoleum Taj Mahal, were his beloved wifes ashes were placed.