For more than 350 years, monsoon rains in Agra, the bustling city where the monument sits, were enough to wash dirt off the structure’s walls. But pollution has worsened over the last couple of decades, and parts of the marble facade have turned yellow and black. Since 2015, workers have scaled the monument’s minarets and walls to correct discoloration and remove layers of grime from the 17th-century structure. January 2018 - Cleaning the monument is time-consuming and challenging. To remove discoloration, workers suspended on scaffolding are caking Fuller’s earth — a mud paste that absorbs dirt, grease and animal excrement, and that is commonly used to treat skin impurities — on the entire monument. The mud is then washed off, leaving a pristine surface. Fortunately we arrived after almost all the cleaning had been finished.