Which is the first Mughal building built entirely in marble?

The Itimad-Ud-Daula's Tomb, built by Mughal Empress Nur Jahan for her father, Itimad-Ud-Daula (Mirza Ghiyas Beg) was the first Mughal structure to be built entirely of white marble. Constructed between 1622 and 1628, it is believed to be the precursor of the magnificent Taj Mahal. Built on the banks of River Yamuna (Agra, Uttar Pradesh, India), the tomb of Itimad-ud- Daulah resembles a silver jewel box in the midst of a garden, sometimes called as the Baby Taj.